SPATIAL AND TEMPORAL ANALYSIS OF AGRICULTURAL WATER REQUIREMENTS IN THE GULF COAST OF THE UNITED STATES¹

Abstract

Competition for water resources is becoming an increasingly important issue in the southeastern U.S. The potential impacts of future precipitation and runoff estimated by a transient global climate model (HADCM2) on competing water resources in the Southeast has been conducted. Issues of agricultural management, irrigation water withdrawals, and water quality were studied over three time periods: 1974–1993, 2020–2039, and 2080–2099 in five water basins identified previously as exhibiting water‐related problems. These basins, which encompass the boundary between Alabama and Mississippi, cover four important agricultural counties in Mississippi. Irrigation water requirements generated by crop growth models for corn, soybeans, and winter wheat were coupled with monthly runoff for the impacted basins estimated by the SWAT water balance model. The results of the study reveal that in the next 20–40 years water availability in the southern portions of the study area will decline as much as 10 percent during times when water requirements for agricultural production are crucial. Maintaining or expanding existing crop yields under future climate regimes may require additional irrigation water and increase competition among other uses such as domestic, industrial, recreational, and ecosystem quality.

Roles of the combined irrigation, drainage, and storage of the canal network in improving water reuse in the irrigation districts along the lower Yellow River, China

“…Efforts have been made to apply the model in agricultural watersheds to simulate plant growth, irrigation management, impact of climate change on irrigation, effects of irrigation on runoff, and interactions among climate, crops, soils, and water (Ritschard et al, 1999;Sophocleous and Perkins, 1999;Gosain et al, 2005;Luo et al, 2008). However, simulating the complicated irrigation canal network of the agricultural watersheds often goes beyond capacities of the current standard version SWAT model.…”

MACROSCALE HYDROLOGIC MODELING FOR REGIONAL CLIMATE ASSESSMENT STUDIES IN THE SOUTHEASTERN UMTED STATES1

“…Many of the regional assessment studies underway in the United States are employing the Vegetationl Ecosystem Modeling and Analysis Project (VEMAP) climatic database (Kittel et at., 1995). Portions of the VEMAP database have been used in several studies in regional assessments (see and Ritschard et at., 1999). The VEMAP data sets contain daily and monthly climate data (Tmax, Tmin, precip., solar rad.)…”

“…Studies (Kittel et at., 1995) have indicated that probable climate change scenarios would include temporal variability of temperature, precipitation, radiation and vegetation (e.g., LAI). Changes in these variables will certainly lead to changes in hydrologic processes such as ET (Ritschard et at., 1999). SWAT allows explicit inclusion of all of the cited atmospheric variables and employs these variables to simulate the relevant hydrologic processes.…”

“…The hydrologic model described above has been employed by the GHCC in a number of locations throughout the southeastern United States for various assessment purposes Ritschard et al, 1999). Implications of short-term climate variability, as well as long term change are under analysis.…”

Assessment of crop growth and soil water modules in SWAT2000 using extensive field experiment data in an irrigation district of the Yellow River Basin

“…SWAT, as a physically-based, spatially distributed hydrological model, has been widely used to simulate the ecological, hydrological, and environmental processes under a range of climate and management conditions throughout the world since 1993 (as indicated by nearly 150 publications documented by Gassman et al, 2007). For example, SWAT was used for assessing the impact of irrigation diversion on river flow in the Midwest of the US (e.g., Ritschard et al, 1999;Hatch et al, 1999;Sophocleous and Perkins, 2000;Bosch et al, 2004;Santhi et al, 2005;Behera and Panda, 2006), for simulating climate change scenarios and their related impacts (Edmonds and Rosenberg, 2005;Izaurralde et al, 2005), and for modeling sediment or nutrient yield (Haggard et al, 2005;Lenhart et al, 2005). The wide applications of SWAT are probably attributed to the comprehensive considerations of hydrologic, biological, and environmental processes, incorporation of management scenarios, availability of parameter databases, and its robustness, flexibility, and user friendliness.…”