Hydrological Extremes

Kelani River Basin in Sri Lanka experiences frequent flooding resulting in loss of lives and properties in this basin. Keeping this in view, a study is taken up for Flood Assessment in Kelani River Basin, Sri Lanka up to Hanwella gauging site using HEC-Hydrologic Modelling System (HEC-HMS) tool. In the study, various available options of HEC-HMS have been considered for evaluation using various goodness of fit criteria, such as NashSutcliffe model efficiency (NSE), Percent Error in Peak, and Percent Error in Time to Peak and Percent error in Discharge Volume (Volume Deviation (D_v)). The Basin model has been selected considering the Kelani river basin up to Hanwella gauging site as a single basin for simulation of flood hydrographs and, in eteorological model, the Gaged weight option, of HEC-HMS, is considered for rainfall analysis. For the transform model or direct runoff model, Clark UH, SCS UH and Snyder UH models are considered. The calibration (manual and automatic) and validation of model parameters are carried out using hourly rainfall-runoff data of the five storm events observed during the monsoon seasons of the years 2017, 2016, 2014 and 2012. The Arc Map-ArcGIS and HEC-GeoHMS have also been used to process the different types of spatial data required as input for the HEC-HMS model application. It is found that the Clark model is the best-suited model for flood assessment of Kelani River Basin. The calibrated and validated Clark model can be very much useful for water managers and decision-makers to adopt structural and non-structural measures to minimize the losses due to frequent occurrence of floods in Kelani River Basin.

The natural factors for flood are mainly topographic characteristics of the land and meteorological properties of the region. The flooding of Gurugram in year 2016 was unexpected and not triggered by the above factors. Type of flooding occurred there is known as pluvial flooding. It happens, when the capacity of local drainage system gets saturated and the system can no more cater to any further surface runoff. The study aims to develop strategies for implementing Sustainable Drainage Systems (SuDS) for mitigating pluvial flooding in Gurugram. For the analysis of potentially vulnerable areas for pluvial flooding, Geographical Information System (GIS) integrated with Multi-parametric Analytic Hierarchy Process (AHP) were employed. At the end of the study, combination of conventional drainage system and SuDS were applied at the critical areas through source control, site control, and regional control measures for mitigating urban flooding in general and pluvial flooding in particular in the case of Gurugram.

In this study, vulnerability assessment of Manipur to flood was done using Iyengar and Sudarshan’s method (unequal weight method). For normalization of indicators, UNDP’s Human Development Index (HDI) (UNDP 2006) was used. Further, regularized incomplete beta function calculator which was available online was used to classify the districts of Manipur based on the composite vulnerability index. The study showed that Churachandpur and Senapati have the highest VIs and lie in the zone of very high vulnerability followed by Thoubal which lie in the high vulnerability zone. This may be because these districts are low on adaptive capacity indicators with moderate on exposure indicators. Bishnupur, Imphal-west, and Ukhrul are least vulnerable to flood followed by Chandel, Imphal-east, and Tamenglong in the vulnerability.

Regional flood frequency analysis (RFFA) was performed using the L-moments approach and employing 12 frequency distributions for the Upper Narmada and Tapi Subzone 3(c). Screening of data was conducted utilizing the Discordancy statistic D_i and regional homogeneity was tested with the help of the heterogeneity measure H_i. Pearson type-III was recognized as the best fit frequency distribution accredited by L-moment ratio diagram and |\( Z_{i}^{\text{dist}} \)|-statistic criteria. Using the Pearson type-III distribution, floods of commonly used return periods were estimated for gauged catchments. Further, a relationship was evolved to evaluate mean annual peak floods (MAPF) involving their catchment areas for ungauged catchments and this relationship is coupled with the RFF relationship for evaluating floods corresponding to different return periods for catchments which are completely ungauged.

Floods being one of the most frequent natural hazards have been causing havoc and destruction in all parts of the world. Every year hundreds of thousands of people get adversely affected by floods in addition to massive biodiversity devastation. Since it is impossible to avoid floods and the after-effects are evident, continuous efforts are in progress to assess and quantify the damages caused by the flood events. With the rapid developments in satellite remote sensing, it is possible to observe the earth surfaces in the flood-prone areas to monitor and map the flood extent and quantify the damages. The European Space Agency’s (ESA) Copernicus is one of the most ambitious Earth Observation (EO) programs having operational satellite constellations providing continuous, accurate, and easily accessible satellite data for the entire globe. This study demonstrates the use of Google Earth Engine (GEE) and Dual-polarized (VV and VH) Sentinel-1 Synthetic Aperture Radar (SAR) data for mapping flooded areas in the Indian state of Punjab. Various districts of Punjab experienced continuous and heavy rain from 15 to 21 August 2019, followed by the release of excess water from the Bhakra Dam resulting in excess discharge in the Sutlej River and its tributaries. As a result, over 300 villages in over a dozen districts of Punjab were inundated, causing extensive damages to crops, especially paddy, and homes in low-lying areas. A change detection approach and thresholding methodology is adopted in Google Earth Engine (Javascript based) Platform to determine the extent of flooding using multiple Sentinel‐1 SAR images captured before and after the floods of August 2019 in Punjab.

Drought characterization is an important aspect for inventing frequency and severity of past drought events. Bundelkhand Region of India has a long-standing history of droughts and starvations. This paper studies drought characteristics in Ken River Basin of Bundelkhand Region encompassing eight districts of central India, namely, Banda, Hamirpur, Mahoba, Chhatarpur, Damoh, Katni, Panna and Sagar, with the primary aim to investigate annual, seasonal and monthly meteorological drought events; analyse critical dry spells and assess supplemental irrigation requirement for critical dry spell period to prevent Kharif season crop failure. An analysis of rainfall data of these eight districts for the period 1980–2016 (37 years) revealed eight drought years and average frequency of drought occurrence was once in 5 years. Sagar District experienced more frequent droughts than did any other. The annual rainfall varied from its 75% normal with probability ranging from 66 to 86% in different districts. The average length of effective monsoon period in the study area was identified as 89 days with mean date of onset as June 22 and withdrawal date as September 19. Thus, paddy varieties of 85–95 days crop duration can be cultivated under rainfed condition. Since the study area has medium black and black soils, cultivation of soybean, maize and shorter duration paddy crops might be preferred. Since the intervening one to two critical spells (period >12 consecutive non-rainy days) during monsoon season in some years caused serious crop loss in the region, it is desirable to have supplemental irrigation during such spells to ensure the success of at least one-season crop.

Droughts are regional climatic phenomena, occurring due to less than average precipitation over a prolonged time at a given place, and subsequently, leading to water deficit and socioeconomic loss. In this analysis, monthly rainfall data of 113 years for 132 districts located in eastern part of India include the states of Bihar, West Bengal, Jharkhand, Orissa and eastern parts of Uttar Pradesh have been used. The percentage deviation in seasonal rainfall has been used to identify commencement, termination and estimation of drought severity. It is observed from the analysis that the frequency of drought in larger part of study area is once in 7 years or more, only in the east Uttar Pradesh, the return period varies from 5 to 6 years. The eastern part of the country hardly experienced extreme droughts while the east Uttar Pradesh is susceptible to the severe events. It was also observed that the eastern part of the country experiences severe droughts once in 19 years or more. The region also faced droughts of 2, 3 and 4 consecutive years. The results obtained from this study will be very useful for making strategies and plans for effective mitigation of droughts in eastern India.

Meteorological drought in Tripura of humid northeast India was investigated using effective drought index (EDI). Gridded rainfall data for the period 1901–2013 of four districts of Tripura were used. The analysis was carried out for premonsoon, monsoon and 6-monthly periods. It is revealed from the study that the Tripura was affected with moderate, severe and extreme droughts during the period of analysis. North Tripura was the worst affected by drought as 5 and 7 extreme droughts were observed during premonsoon and the first half of the year. During monsoon, every district has faced severe drought during all time scales highest number (5) of severe droughts were found in South Tripura. Tripura as a whole experienced a prolonged meteorological drought during May 2006 to July 2009. Maximum number of droughts was observed during monsoon season. Kriging spatial analyst tool of ArcGIS^® 10 was used to generate spatial maps. The results of the study may be beneficial for preparing drought mitigation plans especially during monsoon season.

This paper demonstrates the application of Multifractal Detrended Fluctuation Analysis (MFDFA) to portray the multifractal behavior of Standardized Precipitation Index (SPI) time series of four meteorological subdivisions from Western India, namely, Western Rajasthan, Saurashtra–Kutch-Diu (SK), Marathwada and Kerala at different temporal scales. The Hurst exponents obtained showed good agreement with those computed by Dispersional Analysis (DA) method and it varied from 0.53 to 0.75 in SPI series of different temporal scales of 3, 6 and 12 months. It is noticed that SPI series of different subdivisions are characterized by long-term persistence, which indicated the universal multifractal properties of drought within the subdivisions of the western India irrespective of their climatic conditions. Further, this study quantified the degree of multifractality (DoMF) from the plot of mass exponent and multifractal spectra of different time series, which showed that degree of multifractality shows an increase with accumulation time scale and the strongest DoMF is noted in the data of WR subdivision.

The 480 km coastline of Odisha State is prone to climate-mediated cyclones and floods. The coastal erosion is relatively more vulnerable to climate change, which brings serious negative impacts on coastal regions as most people depend on farming and fisheries for their livelihood. The increase in salinity due to incursion of coastal waters and rise in sea level affects agriculture and availability of fresh water for drinking. Thus, climate variability contributes significantly to poverty, water and food insecurity. The extreme events, perhaps, are the major driver of migration in the coastal belt of Odisha and movement of people to different places. In this study, historical extremes of Odisha coast and their impact on agriculture and water are analyzed in detail.

Temporal and spatial distribution patterns of extreme rainfall in 25 districts of Assam in humid Northeast India were analyzed using gridded (0.25^o × 0.25^o) daily rainfall from 1901 to 2013. Five out of 11 extreme precipitation indices as recommended by ETCCDI were used for the analysis. Results indicated that the consecutive dry days (CDD), consecutive wet days (CWD), annual total wet days precipitation (PRCPTOT), maximum 1-day precipitation (RX1day) and extreme heavy precipitation (R20) were observed to be highest in Dhubri, Hailakandi, Tinsukia, Udalguri and Cachar districts, respectively. The significance of upward (downward) trend at 90% confidence level of all the extreme precipitation indices used was established using Mann-Kendall trend test. Decreasing (increasing) trend in CWD, PRCPTOT and R20 (CDD and RX1day) was revealed during the study period. Spatial maps of the trends in extreme precipitation indices were generated using Kriging spatial analyst tool under ArcGIS^® 10 environment.

Odisha is a disaster-prone state and more often cyclones hit its coast. It is observed that the October month is very sensitive as regards to strike of cyclone. The Super Cyclone of 1999 hit Odisha coast during October 29 and 30, 1999 and the cyclones Phailin and Hudhud in 2013 and 2014 in the same month, respectively. These cyclones are associated with heavy wind speed and also make a huge rainfall on the land. Although the pre-information from Indian Meteorological Department (IMD) regarding the anticipated rainfall in terms of quantitative precipitation forecast (QPF) is well ahead of the arrival of cyclone, there are the uncertainties, like possible diversion of cyclonic track, variation in forecasted rainfall, changes in duration of storm and cyclone, and magnitude of storm surge. The majority of cyclonic storms occurred during October, when all the reservoirs are in full condition due to end of monsoon. Thus, the heavy rain caused due to cyclone may directly affect the reservoir and the delta, resulting in an unprecedented flood. In a very short reaction time hardly few options remain open for flood protection and reservoir operation management. Structural measures like raising, strengthening of embankment may remain open during flood disaster alone but when associated with a cyclone then structural measures are very difficult due to stormy weather. This study discusses a case study toward preventive approaches taken during Phailin emphasizing non-structural approaches.

Every year flash floods, landslides and debris flow caused catastrophic and devastating disasters resulting in huge infrastructure damages and financial losses in the hilly terrains, that is, Uttarkashi, Rudraprayag and Tehri Garhwal districts of Uttarakhand, India. The main reasons for damages in hilly areas are toe erosion, bank erosion and motion of the heavy boulders which roll and bounce along the bottom of the riverbed during cloud burst and concentrated precipitation resulting in high stream power. Most of the guidelines in the literatures focus on traditional river training measures. However, very few researches have been done toward moderation of stream power in steep slope hilly stream. This study examines the August 3, 2012 flood event of Assi Ganga river, Uttarakhand, India using HEC-RAS modeling for stream power moderation and identifies the lack of adequate disaster risk-reduction measures. Finally, the core area which requires further research to reduce the stream power of Assi Ganga type hilly stream has been identified.

The vertical orifice is one of the flow metering devices used to determine the discharge of fluid flowing through it. It is a small opening given at the bottom of the tank with the inlet of fluid placed at the top of the opening through which the fluid is discharging freely into the atmosphere. With these changes in the direction of fluid flow, many losses occur, such as head loss and energy loss. This work aims to determine the orifice coefficients, which are also known as hydraulic coefficients C_d, C_V and C_C to study the dependence of these coefficients on the head of water. In this study, the authors briefly described the vertical orifice, its applications, advantages, disadvantages and limitations of this application. The Torricelli’s law is also explained in brief along with the hydraulic coefficients. The experimental study is done to know the trajectory path of the jet for the different head of water.

Natural or artificial channels are composed of a deep main channel and shallow floodplains flanked either to its one or both sides. When water overflows in banks it causes severe damage to its adjoining floodplain reaches. This necessitates for an accurate estimation of discharge for the remedial measures. In this work, various discharge prediction approaches like single-channel method (SCM) and divided channel methods (DCM) have been demonstrated. Toward this, Manning’s “n” has been evaluated using different roughness formulae. The modified values of Manning’s “n” are used in the SCM for calculation of discharge. These approaches are also applied to various researchers’ datasets. For a comparative study, graphs have been plotted between actual and predicted discharges for various datasets. The mean percentage error has been calculated to evaluate suitable approach for discharge assessment in the compound meandering channel. Again, for more refinement standard deviation of the mean percentage error has been evaluated. Stage–discharge curves are plotted to evaluate the most suitable method of discharge calculation.

Hydrokinetic turbine is considered to be promising for extraction of flow energy in gravity-powered open channels. There are various types of hydrokinetic turbines (Savonius type and Darrieus type) being developed and tested under various researches. Their performance results are available in the literature. The hybrid rotor is a combination of Darrieus and Savonius rotor which can have useful characteristics of both the rotors. A detailed numerical analysis of such system has been carried out and presented in this paper. NACA0018 symmetrical hydrofoil is selected for the development of profile of Darrieus rotor. The study aims to investigate the aerodynamics and performance analysis of hybrid hydrokinetic turbine. In order to enhance the starting characteristics, a 3D model of hybrid rotor along with channel is prepared, and realizable k-ε turbulence model has been employed to perform CFD analysis. Based on the results, it has been found that the hybrid hydrokinetic rotor has better aerodynamics behavior than single Savonius and Darrieus rotor. The performance is found to be better than Savonius rotor. Under future studies, the findings of the study may be useful for developing prototype of such a system for field study.

In this study, scaling of streamwise velocities within the vegetation patch is performed. To simulate such flows, an emergent and sparse vegetation patch is prepared using perspex cylindrical stems with regular spacing along the stream and lateral directions. The vegetation patch is placed in the middle cross-section of the open channel flow (OCF). Three-dimensional flow velocities interior of the vegetation patch are measured using the acoustic Doppler velocimetry (ADV). The measurements are taken along the centerline in the canopy. The measured streamwise velocities interior of the vegetation patch are found to be less than the vegetation-free fully developed flow. In addition, measured streamwise velocities are decreasing in the flow direction within the canopy. Finally, the velocity profile reaches a uniform velocity profile invariant of downstream direction. Upstream of the leading edge, velocity profile follows a power law, whereas it follows a rectangular profile in the fully mixed region inside the patch, and in between the velocity profile is changing gradually. It is important to make the velocity profiles scaled such that they collapse on each other. Mixed scaling in inner and outer variables is used in the investigation and it has been found that the maximum velocity is the appropriate scale.

The use of variable speed machines with voltage source power electronic converters has gained prominence globally in the field of hydro power plant application. The doubly fed asynchronous machine (DFAM) for pump storage plant offers stability over complete range of head variation and load variation. This technological advantage over conventional fixed speed synchronous machines has led to recent development of large capacity doubly fed induction machines (DFIM). One such project employing four DFIMs, each having a capacity of 250 MW and ±6% of speed variation with respect to synchronous speed (500 rpm) is already under operation in Linthal, Switzerland. The maximum efficiency of synchronous hydro-generating units is achieved under rated head and discharge. While operating farther to the rated head, the efficiency of hydro turbine goes down. Therefore, when a wide variation in the water head is available, the machine rotating at fixed speed over the entire range would result in reduction in turbine performance. Variable speed machine provides the solution by adjusting the speed of the turbine over the available water head range to get maximum efficiency. The design of the stator of these machines is identical to that of synchronous machines. The rotor design of the DFAM, however, differs remarkably from conventional (synchronous) machines. The rotor is similar to the stator and equipped with a three-phase winding embedded in slots of a stacked core instead of salient poles. This paper is aimed at computation of annual energy generation from Tehri PSP with a 250 MW machine under the rated head of 188 m and turbine speed of 230.77 rpm for machine having (a) variable speed and (b) fixed speed. The power generation shall be computed for the various head levels taking into account the efficiencies from Hill curves of reversible Francis turbine for fixed as well as variable speed.

Krishna basin is characterized by high rainfall in upper reaches interspersed by rain shadow region with low rainfall and increase in rainfall toward Bay of Bengal. Most of the rainfall is received during southwest monsoon. Many dams have come up across upper catchments of Krishna river which held water up to later stages of monsoon. The downstream flow to the river is being delayed. The rain shadow regions which are depending on flows from upper Krishna are not receiving water in time to tide over dry spells. The releases are taking place after dams are filled up to brim, which is not happening until end of August as occurred during this year. The opportunity cost of holding water is very high, as crops have withered in Rayalaseema and lower reaches due to prolonged dry spells. Analysis is done in the paper for upper Krishna of the cost of holding water by taking into account daily cumulative rainfall from IMD, inflows into Almattti and dry spells experienced in Rayalaseema region. By the time water is released due to floods, it is too late and crops are in irretrievable condition. Nation is paying high cost in terms of GDP without a holistic policy of water releases in large basins due to various constraints. Intelligent water management needs dynamic approach of rain response releases (RRR) which is brought out in the paper taking case study of upper Krishna.

Mathematical modeling usually deals with the technique of solving basic equations representing the natural process. It involves the simulation of flow conditions based on the formation and solution of mathematical relationship expressing known hydraulic principles. Number of computer simulation methods have been developed for the simulation of alluvial river and are in widespread use. The most commonly used simulation methods included in this study are: HEC-RAS, CCHE2D, and MIKE 21C. All these models are based on the derivation of basic principles generally known as the continuity, energy, and momentum equations. To solve these principles, certain methods of numerical approximations are necessary and all these approximations have limitations. The objective of this paper is to illustrate the main features, governing equations, and common limitations of these numerical models.

Gates and hoists based on different principles and mechanism are being used for particular discharge of water through spillways, sluices, intakes, regulators, ducts, tunnels, etc., as well as to facilitate planned and controlled reservoir operation and also for maintenance purposes. These structures manually operated, powered or automatic to restrict the flow of water on a need basis. Different types of gates have been developed/evolved over a long period of time from early wooden logs, caterpillar gates to the latest fixed wheel, slide gate and radial gate to control the design discharge of water via Canal, conduit or spillway. Crest-type radial gates have been constructed in very large sizes, with areas up to 560 m², widths up to 56.5 m, and heights up to 22.5 m. Orifice type radial gates have been constructed with areas up to 114 m, widths up to 12.8 m, heights up to 9.5 m, and heads up to 135 m. [Design Guidelines For Spillway Gates: Chander K. Sehgal, Member, ASCE] For high head installation; radial gates, requiring lesser hoisting capacity and control are much more economical and beneficial than that of other gates. The paper covers the design of high head (i.e. more than 30 m head over sill) regulating (i.e. intended for maintaining particular discharge and not intended for maintenance purpose like stop log gate) radial gate beginning from the selection of material, determination of stresses up to size of its components viz. skin plate, stiffener, girders, arm, trunnion, trunnion pin and hub and its assembly/location of each components. Prevailing softwares like ANSYS applicable for finite element analysis and CATIA for 3D modelling are also being applied for gate design. However, these softwares are costly and require high technical skill and even exporting output (data) from these softwares to another file format may not be possible or much more complex. Unlike those prevailing softwares, Excel Spreadsheets provide complex processing in ways that even people with little technical experience can access. The appearance of every part of the spreadsheet lies under user total control. Therefore, a Microsoft Excel spreadsheet has been developed for the design of components with particular input. It will reduce the tedious calculations of several force analyses and errors in computing for designing. A sensitivity analysis is a useful tool or method to identify the impact of different values of an independent variable upon a particular dependent variable under a given set of assumptions. The paper also shows the graphical representation of the impact of the change in individual input parameter upon the gate design. For this, the same excel sheet has been used for the sensitive analysis with the change in input (variable) parameters, which is very essential during planning stage in the decision-making of suitable location, cost, fabrication, erection aspects of the radial gate.

Maximum tribal farmers in Palghar district, Maharashtra migrate to nearby cities after Kharif cultivation in search of employment because water and land resources become crucial constraints for them during Rabi season. These resources can be managed optimally to make agriculture as a profitable source of livelihood for these farmers. A participatory field study is conducted for this research in selected villages to identify trends of Rabi crops, farmer’s current agricultural practices, their constraints and markets for produce. A linear programming model is developed, which generates alternatives of cropping pattern combinations from a list of selected horticultural crops considering the objectives of local farmers and constraints of available resources. Three cases of cropping pattern (2, 3, 4 crops per season) with two cases of irrigation methods each (furrow and drip system) are created to understand the change in crop selection, cropped area and economics. Drip irrigation system turns out to be more profitable than furrow irrigation system in all the cropping patterns while two crop pattern gives the most profit.

The present study was carried out to determine wetting front dimensions in drip irrigation and to establish a relationship between emitter discharge and wetting front movement in vertical and horizontal directions. The dimensions of wetting front in horizontal and vertical directions for three different emitters with discharge rate of 2, 4 and 8 L per hour (lph), respectively, were observed in medium loam soil. Results revealed that vertical distance of wetting front was increasing rapidly in the beginning but slowly at later stages, and variation of moisture content varied between 16 and 33%. Mathematical equations were developed for estimating the dimension of wetting front in horizontal and vertical directions. The developed equations for 2, 4 and 8 lph dripper showed strong correlation (coefficient of determination i.e. R² is 0.98, 0.982, 0.922 and 0.921, 0.985, 0.958 for horizontal and vertical directions, respectively). Further, it was observed that for same volume discharge, wetting front movement in both directions can vary with variation in water application duration. These mathematical models will be useful to estimate the horizontal and vertical movement of water for the design of drip irrigation system and can also be used in determining irrigation periods for various crops to match their varying root zone temporally.

Food security exists when people at all times have physical, social and economic access to sufficient, safe and nutritious food. The objective of the study is to assess Tanzania’s food security challenges and emphasize the need for precise irrigation. Food security status was quantified using Global Hunger Index (GHI). In 2016, Tanzania figured at 96 out of 118 countries with a score of 28.4 (serious) which needs further improvement, though it is an improvement over the score of 42.4 (alarming) in 2000 with an average consumption of 2205 kcal/capita/day. It has been highlighted that the food security challenges in Tanzania are increased population, undeveloped agricultural technologies, limited income opportunities, unutilized irrigation potential and poor market access. To meet these challenges, precise irrigation is highly recommended. For example, currently, the drip irrigation in Tanzania covers less than 0.1% of irrigated land and there is plenty of scope for precise irrigation. On-farm adaptive studies through participatory programs and farmers’ field schools will help in capacity building during adaption.

The most effective means to conserve water appears to be carefully managed deficit irrigation delivery system. The present study deals with the effective water management practices to deficit irrigation based on different soil moisture depletion level (SMDL) with combination of soil mulch and without mulch to enhance water use efficiency and yield output of finger millet as substitute of summer rice. Finger millet experiments were conducted at research farm of Indira Gandhi Krishi Vishwavidyalaya, Raipur during summer season in 2014, 2015, and 2016 to evaluate two main treatments of moisture conservation (soil mulch and without mulch) with combination of five submain treatments, i.e., 30% SMDL (soil moisture depletion level), 40% SMDL, 50% SMDL, 60% SMDL, 70% SMDL. We also conducted summer rice experiment parallel to assess the technoeconomic comparison with summer finger millet. The result shows that the higher grain yield of finger millet in combination of soil mulch with 60% SMDL gave 23.48 q ha⁻¹ under split plot design. The water use efficiency is also higher in combination of soil mulch with 60% SMDL (6.21 kg ha⁻¹mm⁻¹) as compared with combination of soil mulch with 50% SMDL (6.10 kg ha⁻¹mm⁻¹). On the basis of pooled data of 3 consecutive years, it can be concluded that summer ragi water requirement is 37.5 cm, which can be accomplished by eight numbers of irrigation. It can be concluded that 75.5 cm of water per hectare can be saved if summer rice is replaced by finger millet. The water saving can increase the cultivated area more than three times under summer finger millet as compared with summer rice.

The rise in population and climate variability has adversely affected the various urban infrastructures in the world. Despite abundant availability of water resources, providing safe and adequate drinking water to the masses in the famous harbour city of Freetown in Sierra Leone is a big challenge. The city has problems such as Institutional framework and its capabilities, social issues like affordability, perception, social inclusion, and other managerial issues. Besides these, it has technical issues like water conservation, leak detection, and water quality monitoring and modelling. This study highlights various such issues that are important for the sustainability of water supply in this most important harbour city of West Africa. The study assesses the sustainability of the existing water supply system and recommends various measures for improvement. It has been noticed that the sustainability index for the Freetown is of the order of 0.467, which is termed as ‘poor’. The main reasons for such poor sustainability are the weak institutional framework, low enforcement, low investment, and low paying capability of the people. It is feared that with the rise in population, water demand will increase manifold that will aggravate the problem in near future. The study suggests various techno-managerial measures to improve the sustainability of water supply in the city.

Reference evapotranspiration (ET0) is crucial to water resources and irrigation planning and scheduling. ET0 can be estimated directly from the evaporation pan data via the pan coefficient (K_p) or indirectly with empirical methods. Four common K_p equations (i.e., Snyder, Cuenca, Orange, and Allen and Pruitt) to calculate K_p coefficients to estimate ET0 were evaluated. In comparing mean deviation, coefficient of determination, and root mean square error (RMSE), the Snyder and Orange equations closely produced the K_P value with the observed K_P (FAO-56 PM/Epan) in the study area. ET0 was also estimated using seven estimation methods and compared with the Penman–Monteith (PM) result since PM is recommended as the standard evapotranspiration estimation method. Empirical methods, namely, PM, Priestley–Taylor, Turc, Makkink, Abtew, Hargreaves, Blaney–Criddle, and Enku temperature methods, were evaluated. Results revealed that, except Hargreaves and Priestley–Taylor, all methods have a correlation of 0.82–0.98. The Turc method showed the closest mean daily and yearly ET0 with PM followed by Enku and Makkink, whereas Hargreaves and Priestley–Taylor showed relatively highest overestimated and underestimated from PM with 2.91 and 1.62 of RMSE, respectively. In general, Turc, Enku, and Makkink perform better and are closest to the PM method.

Capillary rise through a shallow water table is a vital source of water transport in the soil moisture movement system. However, field observation of the capillary rise is difficult, nearly impractical, and economically unfeasible. Therefore, dependency on the adaptation of capillary rise models increases. The present study aims to evaluate the performance of four models for estimating the capillary rise from the crop root zone of Wheat (Triticum aestivum). Essential model parameters are observed from field experiments conducted at Hamirpur (India) under controlled conditions for two consecutive crop seasons. Qualitative and quantitative analysis is carried out between the observed and estimated cumulative capillary rise. Results suggest that Modified Averianov formula has better agreement with observed values with RMSE, R², and Nash-Sutcliffe efficiency values of 0.04, 0.71, 0.74, and 0.06, 0.67, 0.72 during 2016 and 2017 growing seasons, respectively. The results of the study can be utilized for providing intelligent information in designing irrigation schedules, and the number of irrigation events under the effect of the shallow water table to obtain optimum yield and subsequently, help in optimizing the use of irrigation water.

Semi-arid agriculture (55% of net sown area) in India suffers from rainfall vagaries like extreme events of high intensity and drought due to climate change which damages the crops and losses to the farming community. In order to assess the crop loss due to extreme events and changes in the soil water balance and crop coefficients due to increased CO₂ and Temp, the Supervisory Control and Data Acquisition (SCADA) integrated with Programmable Logic Controller (PLC) and data loggers have been used for integrating soil moisture sensors at different depths (15–90 cm), turbidity sensors, tipping bucket counter sensor for rainfall simulator with 3 soil bins of size 6 × 3 m with 1 depth soil column. The system has portable rainfall simulator which can move over soil bins for operating the rainfall simulator with rainfall intensities of 75–150 mm/h. PLC was programmed to bring HMI controls for operating rainfall simulator at different intensities and durations, and the slope of the soil bins varying from 1 to 10% through hydraulic lifts. The lysimeter system with open-top chambers of CO₂ + Temp, eCO₂, eTemp and control at ambient conditions has been constructed by using the load cells for measuring the weight of soil, sensors for soil moisture measurement with 4–20 mA electric signal at different depths ranging from 15 to 120 cm. CO₂ sensor and RTD temperature sensors have been used for monitoring the CO₂ and temperature. The systems are configured for maintaining 550 ± 50 ppm CO₂ and temperature increase from 1 to 5 °C from SCADA through PLC. The systems are designed with the state of art process automation smart instrumentation for assessing the soil water balance changes with respect to changes in temp and CO₂ levels through lysimeters and the production loss and soil, water and nutrient losses from soil column due to occurrence of extreme events of high-intensity rainfall.