Abstract
As a well-built, distributed hydrological model, the Soil and Water Assessment Tool (SWAT) has rarely been evaluated at small spatial and short temporal scales. This study evaluated crop growth (specifically, the leaf area index and shoot dry matter) and daily evapotranspiration at the hydrological response unit (HRU) scale, and SWAT2009 was modified to accurately simulate crop growth processes and major hydrological processes. The parameters of the modified SWAT2009 model were calibrated using data on maize for seed from 5 HRUs and validated using data from 7 HRUs. The results show that daily evapotranspiration, shoot dry matter and leaf area index estimates from the modified SWAT2009 model were satisfactory at the HRU level, and the RMSE values associated with daily evapotranspiration, shoot dry matter, and leaf area index were reduced by 17.0%, 1.6%, and 71.2%, compared with SWAT2009. Thus, the influences of various optimal management practices on the hydrology of agricultural watersheds can be effectively assessed using the modified model.
Highlights
An irrigation district is a composite ecosystem with anthropogenic and natural elements [1].In an irrigation district, the processes of artificial irrigation and evapotranspiration are critical for water resource management and are important in the hydrological cycle
The model simulations were initiated using a table of Kcb values; p and soil evaporation parameter values were those recommended by Allen et al [49]; and the initial Ze, TEW and REW values of 0.1 m, 28 mm and 8 mm, respectively, were used for silt-loam soils
The results indicated that BLAI, leaf area index (LAI), LAIMX2, and LAIMX1 were the primary parameters in the mgt, crop, sol, gw, and rte input files used in the Soil and Water Assessment Tool (SWAT) model (Table 5)
Summary
An irrigation district is a composite ecosystem with anthropogenic and natural elements [1].In an irrigation district, the processes of artificial irrigation and evapotranspiration are critical for water resource management and are important in the hydrological cycle. To understand and analyse watershed processes and interactions, assess management scenarios, test research hypotheses, and evaluate the influence of changing irrigation [2], a coupled hydro-agronomic model is needed. Model [3] and Soil and Water Assessment Tool (SWAT) [4,5], have been used to support water quality management, water resource analysis, and soil erosion assessment in agricultural watersheds. Among these models, SWAT is one of the best for the long-term simulation of watersheds dominated by agricultural land use.
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