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Managing water resources in agriculture and watersheds: Modeling using GIS and dynamic simulation

Sekar Iyyapazham, University of Massachusetts Amherst


The availability of fresh water is becoming an increasing concern around the world. Modern agriculture has made a transition from traditional agriculture, which often impacts watershed systems. Current enterprising agriculture yields monetary benefits but at the same time can impact environmental outcome. Water resource impacts vary from micro to macro scale. Chapter 1 starts with an introduction. In Chapter 2, I develop an integrated dynamic-based model at farm scale to evaluate the economic and environmental effects of alternative agricultural best management practices (BMPs) on overall sustainability of integrated farming system. It is an integration of a farm simulation model, soil erosion model and dynamic based model. Economic and environmental dynamic simulations are performed over a time horizon for each management practice. Marginal efficiency analysis is performed for examining economically efficient crop support practice with the consideration of change in environmental parameters' and profit accrued from the farm. Scenario outcomes of the stochastic modeling simulation results show varied impacts on sustainability of the farm-balanced scenario performs better overall. Chapter 3 discusses hydrology model at watershed scale to assess conjunctive water harvesting potentials in an urbanizing watershed system. I develop a spatially explicit method to evaluate costs of harvesting and potential benefits in water harvesting. It involves an evaluation of surface and groundwater hydrology in developed and undeveloped regions of the watershed. I develop prioritization maps to characterize conjunctive harvesting potential that is based on benefits and costs. The results demonstrate that a spatially variable harvesting strategy can be used to minimize runoff loss and to augment water supplies. A spatially variable approach that incorporates economic criteria to hydrologic assessment can be used to enhance efficiency related to water harvest and supply management. In Chapter 4, I develop a watershed based policy framework that identifies four policy types that target depletion, recharge, contamination and treatment. The policy package incorporates a mix of policies that target quantity and quality dynamics. The socio-economic implications of excessive extraction of ground water are assessed with the sustainability indicators of productivity from farms, distribution of income among different categories of farmers, groundwater level, and quality. A watershed based policy package covering both structural and nonstructural policies is suggested for achieving sustainability of water resources. Water quality degradation at macro scales involves economic as well as demographic factors. In Chapter 5, I use the concept of Environmental Kuznets Curve to examine the relationship between water quality degradation and economic development, and test the hypothesis of differences in functional relationship for nitrogen, phosphorus, suspended solids, fecal coliform and dissolved oxygen. The results show that the behavior of EKC is different for different water quality indicators. Nitrogen, phosphorous and suspended solids exhibit a U-shaped curve while fecal coliform and dissolved oxygen show N-shaped EKC curve. As transformation occurs from agriculture economy to industrialized economy, water quality improves with the reduction in nutrient and physical contaminants. The dissertation ends up with a conclusion in Chapter 6.

Subject Area

Agricultural economics|Environmental science

Recommended Citation

Iyyapazham, Sekar, "Managing water resources in agriculture and watersheds: Modeling using GIS and dynamic simulation" (2007). Doctoral Dissertations Available from Proquest. AAI3254957.