Introduction
Study area and data
Description of the study area
Data description
Year | Satellite | Sensor | Path/Row | Resolution | Acquisition date (day/month) | Cloud cover |
---|---|---|---|---|---|---|
2001 | 7 | ETM + | 148/37,149/36–37,150/36–37 | 30 m | 2,4,11/09 | < 10 |
2009 | 5 | TM | 148/37,149/36–37,150/36–37 | 30 m | 5,10,12,19/09 | < 10 |
2018 | 8 | OLI | 148/37,149/36–37,150/36–37 | 30 m | 12,21/09 | < 10 |
Methodology
LULC classification
Class code | LULC class | Description |
---|---|---|
1 | Agriculture | Wheat, rice, fodder crops and vegetables |
2 | Forest | Evergreen and deciduous forests and orchards like apple, pear, walnut, almond etc. |
3 | Grass | This class includes mountainous rangelands, state owned grass lands and sparsely vegetated area |
4 | Settlement | Residential areas, roads, industrial zones, barren land and dry stream channels |
5 | Water | Rivers, lakes, ponds and snow cover |
SWAT hydrological model
Parameters | Description | Unit | |
---|---|---|---|
1 | GW_DELAY | Groundwater delays | Days |
2 | GW_REVAP | Groundwater revap coefficient | – |
3 | GWQMN | Threshold depth of water in shallow aquifer required for return flow to occur | mm |
4 | REVAPMN | Threshold depth of water in shallow aquifer required for “revap” to occur | mm |
5 | RCHRG_DP | Deep aquifer percolation fraction | – |
6 | ALPHA_BF | Base flow alpha factor | Days |
7 | CN2 | Initial SCS runoff curve number for moisture condition II | – |
8 | CH_K2 | Effective hydraulic conductivity in the main channel alluvium | mmh−1 |
9 | CH_N2 | Manning’s “n” value for the main channel | – |
10 | EPCO | Plant uptake compensation factor | – |
11 | ESCO | Soil evaporation compensation factor | – |
12 | SOL_AWC | Available water capacity of the soil | mmmm−1 |
13 | SOL_K | Saturated hydraulic conductivity | mmh−1 |
14 | SUB_SFTMP | Snowfall temperature | °C |
15 | SUB_SMTMP | Snow melt base temperature | °C |
16 | SUB_SMFMX | Maximum melt rate for snow on June 21 | mm°C−1 day−1 |
17 | SUB_SMFMN | Minimum melt rate for snow on December 21 | mm°C−1 day−1 |
18 | SUB_TIMP | Snow pack temperature lag factor | – |
19 | SNOCOVMX | Minimum snow water content that corresponds to 100% snow cover | mm |
20 | SNO50COV | Snow water equivalent that corresponds to 50% snow cover | mm |
21 | SOL_D | Soil bulk density | gcm−3 |
22 | SOL_Z | Depth from soil surface to bottom of layer | mm |
23 | ALPHA_BNK | Base flow alpha factor for bank storage | Days |
24 | CH_D | Average depth of main channel | m |
25 | CH_L | Length of main channel | m |
26 | CANMX | Maximum Canopy storage | mm |
27 | SURLAG | Surface runoff lag coefficient | – |
28 | PLAPS | Precipitation lapse rate | mmKm−1 |
29 | TLAPS | Temperature lapse rate | °CKm−1 |
30 | SHALLST | Initial depth of water in the shallow aquifer | mm |
Results and discussion
Land use and land cover classification
LULC class | 2001 | 2009 | 2018 | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
UA % | PA % | OA % | KC % | UA % | PA % | OA % | KC % | UA % | PA % | OA % | KC % | |
Agriculture | 93 | 91 | 90 | 89 | 93 | 92 | 92 | 90 | 95 | 94 | 95 | 94 |
Forest | 94 | 93 | 92 | 94 | 96 | 97 | ||||||
Grass | 83 | 90 | 82 | 88 | 95 | 94 | ||||||
Settlement | 83 | 83 | 92 | 93 | 94 | 93 | ||||||
Water | 91 | 93 | 93 | 94 | 100 | 100 |
LULC 2018 | Total | ||||||
---|---|---|---|---|---|---|---|
Agriculture | Forest | Grass | Settlement | Water | |||
LULC 2001 | Agriculture | 6998 | 2130 | 716 | 346 | 102 | 10,292 |
Forest | 323 | 8455 | 328 | 32 | 173 | 9311 | |
Grass | 507 | 1533 | 9594 | 198 | 455 | 12,287 | |
Settlement | 0 | 0 | 22 | 656 | 14 | 692 | |
Water | 0 | 0 | 16 | 28 | 771 | 815 | |
Total | 7828 | 12,118 | 10,676 | 1260 | 1515 | 33,397 |
LULC class | 2001 | 2009 | 2018 | Change 2001–2018 | ||||
---|---|---|---|---|---|---|---|---|
Area (Km2) | Area (%) | Area (Km2) | Area (%) | Area (Km2) | Area (%) | Area (Km2) | Area (%) | |
Agriculture | 10,292 | 30.82 | 8455 | 25.31 | 7828 | 23.43 | − 2463.88 | − 6.39 |
Forest | 9311 | 27.88 | 10,745 | 32.17 | 12,118 | 36.28 | 2806.87 | 8.4 |
Grass | 12,287 | 36.79 | 11,989 | 35.90 | 10,676 | 31.97 | − 1611.24 | − 4.82 |
Settlement | 692 | 2.07 | 1031 | 3.08 | 1260 | 3.77 | 567.84 | 1.7 |
Water | 815 | 2.44 | 1177 | 3.52 | 1515 | 4.53 | 700.42 | 2.09 |
Total | 33,397 | 33,397 | 33,397 |
Sensitivity analysis
Sr. no. | Parameter | Category | Initial range | Neelum basin | Kunhar basin | Upper Jhelum basin |
---|---|---|---|---|---|---|
1 | GW_DELAY | Groundwater | 0–500 | 417.03 | 207.77 | |
2 | GW_REVAP | Groundwater | 0.02–0.2 | 0.05 | ||
3 | GWQMN | Groundwater | 0–5000 | 3308.45 | 2959.75 | |
4 | REVAPMN | Groundwater | 0–500 | |||
5 | RCHRG_DP | Groundwater | 0–1 | 0.48 | ||
6 | ALPHA_BF | Groundwater | 0–1 | 0.45 | 0.31 | 0.05 |
7 | CN2 | Runoff | ± 0.25 | − 0.23 | − 0.03 | 0.16 |
8 | CH_K2 | Channel | 0.001–200 | 107.98 | 158.87 | |
9 | CH_N2 | Channel | − 0.01–0.3 | 0.03 | 0.19 | |
10 | EPCO | Evaporation | 0–1 | |||
11 | ESCO | Evaporation | 0–1 | 0.10 | ||
12 | SOL_AWC | Soil | ± 0.20 | |||
13 | SOL_K | Soil | ± 0.20 | − 0.04 | ||
14 | SUB_SFTMP | Snow | − 5–5 | − 2.19 | − 2.77 | 0.96 |
15 | SUB_SMTMP | Snow | − 5–5 | 1.24 | 4.32 | − 2.11 |
16 | SUB_SMFMX | Snow | 0–10 | 3.99 | 2.62 | 8.15 |
17 | SUB_SMFMN | Snow | 0–10 | 5.06 | 3.08 | 4.39 |
18 | SUB_TIMP | Snow | 0–1 | 0.61 | 0.50 | 0.73 |
SWAT calibration and validation
Stations (Rivers) | Calibration | Validation | ||||
---|---|---|---|---|---|---|
NSE | R2 | Pbias | NSE | R2 | Pbias | |
Azad Pattan (Jhelum) | 0.71 | 0.74 | − 13.6 | 0.71 | 0.73 | 1.1 |
Kohala (Jhelum) | 0.71 | 0.77 | − 14.2 | 0.70 | 0.74 | − 2.2 |
Domel (Jhelum) | 0.75 | 0.80 | − 12.3 | 0.77 | 0.81 | 5.6 |
Muzaffarabad (Neelum) | 0.56 | 0.71 | − 14.4 | 0.52 | 0.59 | − 12.9 |
Garhi Habibullah (Kunhar) | 0.72 | 0.72 | − 4.6 | 0.57 | 0.61 | 13.1 |
Impacts of LULC change on the hydrology of JRB
Historical land use change impacts
Historical LULC | Surface runoff (mm) | Base flow (mm) | Water yield (mm) | Evapotranspiration (mm) |
---|---|---|---|---|
LULC 2001 | 539.03 | 222.56 | 927.67 | 462.22 |
LULC 2009 | 527.21 | 225.3 | 920.58 | 469.41 |
LULC 2018 | 508.15 | 232.88 | 910.87 | 479.60 |
Changes 2001–2018 | − 30.88 (− 5.7%) | + 10.32 (4.6%) | − 16.80 (− 1.8%) | + 17.38 (3.7%) |
Extreme LULC scenarios impacts
Scenarios | Surface runoff (mm) | Base flow (mm) | Water yield (mm) | Evapotranspiration (mm) |
---|---|---|---|---|
All agriculture converted to forest | 465.63 | 247.98 | 885.84 | 504.0 |
All grass converted to forest | 439.95 | 264.38 | 883.23 | 506.9 |
All grass + agriculture converted to forest | 421.09 | 271.25 | 873.01 | 515.7 |
Impact of LULC changes on ET and WY at the sub-basin scale
Basin no. | Fraction LULC class area | ET (mm) | WY (mm) | ||||||
---|---|---|---|---|---|---|---|---|---|
2001 | 2009 | 2018 | 2001–2009 | 2009–2018 | 2001–2018 | 2001–2009 | 2009–2018 | 2001–2018 | |
2 (Kunhar Basin) | AGRL:0.14 | AGRL:0.09 | AGRL:0.11 | − 2.16 | − 3.05 | − 5.21 | 54.54 | 21.02 | 76.32 |
FRST:0.14 | FRST:0.13 | FRST:0.12 | |||||||
RNGE:0.62 | RNGE:0.60 | RNGE:0.52 | |||||||
URMD:0.04 | URMD:0.05 | URMD:0.08 | |||||||
WATR:0.06 | WATR:0.13 | WATR:0.17 | |||||||
3 (Neelum Basin) | AGRL:0.11 | AGRL:0.09 | AGRL:0.10 | − 0.50 | − 2.51 | − 3.00 | 24.02 | 55.15 | 59.04 |
FRST:0.29 | FRST:0.29 | FRST:0.29 | |||||||
RNGE:0.56 | RNGE:0.55 | RNGE:0.48 | |||||||
URMD:0.02 | URMD:0.02 | URMD:0.02 | |||||||
WATR:0.02 | WATR:0.05 | WATR:0.11 | |||||||
15 (Upper Jhelum Basin) | AGRL:0.37 | AGRL:0.37 | AGRL:0.22 | 13.21 | 31.93 | 45.14 | − 11.23 | − 34.56 | − 45.01 |
FRST:0.20 | FRST:0.25 | FRST:0.38 | |||||||
RNGE:0.38 | RNGE:0.29 | RNGE:0.28 | |||||||
URMD:0.04 | URMD:0.07 | URMD:0.10 | |||||||
WATR:0.01 | WATR:0.02 | WATR:0.02 | |||||||
16 (Upper Jhelum Basin) | AGRL:0.53 | AGRL:0.59 | AGRL:0.66 | 39.44 | 19.94 | 59.38 | − 11.99 | − 23.23 | − 35.22 |
FRST:0.12 | FRST:0.17 | FRST:0.21 | |||||||
RNGE:0.34 | RNGE:0.22 | RNGE:0.11 | |||||||
URMD:0.01 | URMD:0.02 | URMD:0.02 | |||||||
WATR:0.00 | WATR:0.00 | WATR:0.00 | |||||||
17 (Upper Jhelum Basin) | AGRL:0.19 | AGRL:0.15 | AGRL:0.13 | 11.96 | 39.97 | 51.93 | − 6.30 | − 42.02 | − 48.32 |
FRST:0.19 | FRST:0.25 | FRST:0.29 | |||||||
RNGE:0.54 | RNGE:0.51 | RNGE:0.49 | |||||||
URMD:0.04 | URMD:0.04 | URMD:0.05 | |||||||
WATR:0.04 | WATR:0.05 | WATR:0.04 |