Sensitivity of hydrology and water quality to variation in land use and land cover data

Abstract

Land use and land cover (LULC) change is critical to hydrologic study as it affects surface runoff, sediment yield,and nutrient load from watersheds. Change in LULC is a continuous process in agricultural watersheds as per thegrowing and harvesting seasons. In this study, monthly LULC data layers were generated for the Big SunflowerRiver Watershed (BSRW), Mississippi by classifying cloud free Landsat images from 2014 to 2018 and combiningthem according to the season in order to obtain dominant LULC data layers for spring, summer, and fall. About60 % of the total land area in summer was cultivated land, whereas only 20 and 5 % of the total land area werecultivated land during fall and spring, respectively. The rest of the total land area was constantly covered withurban, forest, and water for the three seasons. The overall accuracy and kappa coefficient ranging from of 87 %to 92 % and 0.8 to 0.90 was obtained during accuracy assessment of the seasonal LULC data layers. This suggestedthat the seasonal data layers can reasonably be used in the Soil and Water Assessment Tool (SWAT) toanalyze the effects of LULC data variation on hydrology and water quality of BSRW. SWAT was calibrated andvalidated for streamflow, sediment yield, and nutrient concentration using the summer LULC data layer andthose parameters were applied to the models using the spring and fall LULC data layers. SWAT output for runoff,sediment yield, and nutrient load was found to be very sensitive to the change in LULC data layers. The averageamount of runoff and sediment yield was higher during the summer while total nitrogen and total phosphorousyields were higher during the fall and spring, respectively. Agricultural operations are usually conducted duringthe summer and fields are mostly barren during the spring and fall. The use of seasonal LULC data layers is verybeneficial to the scientific community as they can better explain the seasonal variation in hydrology and waterquality as compared to the annual cropland data layer that is available for a single season of a year.

Citation

Risal, Avay; Parajuli, Prem B.; Dash, Padmanava; Ouyang, Ying; Linhoss, Anna. 2020. Sensitivity of hydrology and water quality to variation in land use and land cover data. Agricultural Water Management. 241: 106366-. https://doi.org/10.1016/j.agwat.2020.106366.