WOLF RIVER

Wolf River Basin in West Tennessee and North Mississippi

Table of Contents

Chapter 1: Introduction3

Chapter 2: Literature Review5

Chapter 3: Methodology7

Study area7

Hydrology model of Wolf River Basin8

Chapter 4: Results and discussion9

Calibration and validation in the Wolf River Basin9

Effect of parameter transfer on hydrologic responses10

Chapter 5: Conclusion11

References12

Chapter 1: Introduction

Watershed models are valuable tools used in the study of impacts of land use/cover (LULC) changes on hydrology. We use the Soil and Water Assessment Tool (SWAT) to study the impacts of LULC changes in Wolf River Basin in West Tennessee and North Mississippi, where flow data did not exist at the onset of the study.

Quantifying the impacts of land use and land cover (LULC) changes on the hydrologic processes and water balance of river basin has been an area of interest to hydrologists in recent years (Arnold, 1995). Little is known so far if there is a well-defined quantitative relationship between the LULC properties and the runoff generation mechanisms. The assessment of future LULC changes with respect to their hydrological impacts is still an unsolved problem. Several methods were developed to study the implications of LULC changes on hydrologic processes, such as the paired catchments approach, time series analysis (statistical method), and hydrological modelling. Among these approaches, hydrological modelling has been widely applied in many different places in the world as it requires fewer resources and provides more flexibility (Yokoo, 2001).

Fohrer et al. (2001) assessed the hydrologic response to LULC changes in four meso-scale watersheds in Mississippi with different LULC distributions. The model performance for changing LULC was then tested in an artificial watershed with one crop at a time and one underlying soil type to eliminate the complex interactions of natural watersheds. Simulation results showed that LULC changes on the annual water balance was moderate. Surface runoff was most susceptible to LULC change at both the artificial and the natural catchments.

Chapter 2: Literature Review

The term regionalization has its roots in the process of regime classification and watershed grouping. It has later been extended in the rainfall-runoff modelling context to refer to the transfer of parameters from neighboring gauged watersheds (also called donor watersheds) to an ungauged watershed. Nowadays, the concept of regionalization applies to all methods aimed at estimating model parameter values on any ungauged watershed in a definable region of consistent hydrological response. Several methods are available in the literature for the transferring of model parameters (Yokoo, 2001).

Regionalization based on regression is the most popular method, which attempts to link parameter values to climate and watershed physical characteristics, such as annual rainfall, temperature, area, slope, and LULC in a gauged watershed. Another commonly used approach is regionalization based on physical similarity. Generally, information is transferred between neighboring watersheds, not necessarily geographically connected but rather in terms of observable watershed descriptions (Oudin et al., 2008). Parameters are transferred from one or many donor watersheds, whose physical descriptors are similar to the ungauged one, based on a synthetic rank that reflects the similarity of all physical descriptors between donors and ...