The Geospatial Hydrology and Ecological Modeling Group at Vernon is currently conducting research in the following areas:
- Assessing the impacts of biofuel-induced land use change on hydrology and water quality in the southwestern US cotton belt region.
- Evaluating the impacts of grazing management practices on water catchment functions in Southern Tallgrass Prairie.
- Development and evaluation of efficient irrigation and crop management strategies under current and future climate change scenarios.
- Long-term assessment of groundwater quality and availability in Texas.
1. Assessing the impacts of biofuel-induced land use change on hydrology and water quality in the southwestern US cotton belt region
Global biofuel production increased from about 16 billion liters in 2000 to over 100 billion liters in 2010. The demand for biofuels is expected to further increase by 15-fold by mid-century and the demand for land for biofuel production is expected to increase from around 30 million ha in 2010 to over 100 million ha by 2050. The increasing demand for land for biofuel production in the U.S. has led to increased competition for productive agricultural land, shifts in land use among different crops, and conversion of land from other uses into biofuel production. About half of the targeted second-generation biofuels for 2022 is identified to be produced in the Southeastern Region of the U.S, which includes several states traditionally in the U.S. Cotton Belt. USDA estimates that approximately 11.4% of existing croplands and pastures in this region will be required to be under second-generation biofuel production to meet the target.
The overall goal of this study is to assess the hydrologic and water quality impacts associated with the change in agricultural land use to biofuels-dominated cropping systems in the semi-arid Southwestern U.S. Cotton Belt region. The specific objectives are to:
- Assess the impacts of potential land use change from cotton to cellulosic bioenergy crops such as Alamo switchgrass, Miscanthus, big bluestem and biomass sorghum on water balances and water quality at the landscape and watershed scales using SWAT, APEX and Integrated SWAT-APEX models.
- Study the effects of historic and future climate variability on water balances, sediment and nutrient loads, and crop yields under baseline and biofuel-induced land use change scenarios.
2. Evaluating the impacts of grazing management practices on water catchment functions in Southern Tallgrass Prairie
Both rural and urban populations depend on ecosystem services provided by rangelands. These services include maintaining stable and productive soils, delivering clean water, and sustaining plants, animals and other organisms that support livelihoods and human aesthetic and cultural values. Consequently, it is important for those managing the land to adopt management practices that maintain or restore soil and ecosystem health and resilience. Each ranch landscape and watershed is unique as it is composed of different soils and topography with different management history. We therefore need to know how the individual ranch landscapes and watersheds respond to different grazing management practices in terms of hydrological function. In addition, it is important to assess the impacts of projected future climate on ecosystem services under different grazing management practices and suggest potential adaptation and/or mitigation strategies. The objectives of this study are to:
- Evaluate water storage, water erosion and water quality consequences of different grazing management strategies in north central Texas
- Assess the impacts of climate variability and change on water catchment functions under different grazing management practices, and suggest potential adaptation and/or mitigation strategies.
3. Development and evaluation of efficient irrigation and crop management strategies under current and future climate change scenarios
The semi-arid Texas High Plains and Rolling Plains region is one of the most intensive agricultural regions in the world. Agriculture in this region is facing many challenges from rapid declines in groundwater levels, recurring droughts in the recent times, and projected warmer and drier summers in the future. We use different crop modules available in the DSSAT Cropping System Model to develop and evaluate environmentally and economically sustainable cropping systems and production practices for the Texas High Plains and the Texas Rolling Plains under the current and future climate change scenarios. The specific objectives of this study are to:
- Evaluate the cotton, wheat and sorghum modules in the DSSAT cropping system model for the Texas High Plains and Rolling Plains region using the measured data from ongoing and past field experiments.
- Develop and evaluate efficient irrigation and crop management strategies for crop production, and formulate decision support tools.
- Assess the impact of historic and future climate variability and change on crop production, water use and soil carbon sequestration.
- Evaluate the feasibility of growing cover crops in the Texas High Plains and Rolling Plains cropping systems to improve soil health.
Texas is largely dependent upon groundwater resources. About 59% of state’s total water supply and about 99% of the rural household needs are met from the groundwater extracted from 9 major and 21 minor aquifers of the state. Future projections, however, indicate about 30% reduction in water availability over the next few decades due to adverse climatic conditions and depletion of major aquifers. Numerous studies have documented groundwater quality degradation in several parts of the state, which threatens community welfare and sustainable development. In the face of snowballing crises of water availability and water quality deterioration, the overall objective of this study is to identify long-term spatio-temporal trends in groundwater levels and groundwater quality across the state and unravel the nexus between the two. We integrate different geochemical, graphical, and statistical techniques within a geospatial environment to seek answers to questions such as:
- Where are the hotspots of groundwater contamination and groundwater decline?
- Is groundwater contamination a manifestation of water-level changes?
- What are the potential causes of contamination and water-level decline?
- What are the effects of different agricultural and land management practices on water quality and availability?
- How to distinguish between natural and anthropogenic processes to understand relative impacts of each on groundwater resources?