Applying Water Quality Modeling to Regulating Land Development in a Watershed

Abstract

Achieving a balance between land development and environmental protection has always been a challenge for many policy makers around world. The purpose of our project is to build a management system for protected drinking water source watersheds where land development is restricted for reasons of water health and drinking safety. Ideally under this proposed management system, land development is not considered taboo, but can proceed with preconditions. We first divided a protected area into two protection zones for different types of regulations. In the first zone, any type of land development is strictly prohibited, as the currently dominant philosophy for watershed protection. In the second zone, development is allowed but only when a permit with more environmental protection requirements is granted by a responsible governmental agency. In response to land development regulations, we proposed three compensation programs to the landowners of the protected watersheds to reduce their resistance on the inclusion of their properties into the designated protected areas. How to delineate and divide a protected area for different levels of regulation is thus a concern of all parties involved in management and compensation programs. In this paper, we demonstrate a case study on the Kao-** River Watershed, a subtropical watershed with highly heterogeneous land uses and a wide range of elevations in southern Taiwan. Through this study, we empirically examined the feasibility of the proposed management and compensation schemes. The targeted water pollution abatement goals were regarded as the basis of determining the area requirements for these two types of protection zones. Under this principle, the Arc/View GIS software and two water quality prediction models, QUAL2E and GWLF, were repeatedly applied to simulate the effects of water pollution reduction with different acreage of development-restricted areas. The optimal areas of the protected zones from the modeling results were further used to estimate the amounts of compensation fees based on the three following mechanisms: land banking, conservation easement, and transferable development rights.