A Monitoring/Modeling Strategy for 208 Implementation

Abstract

ABSTRACT AN increased emphasis on obtaining and preserving our nation's water quality has led to the need for in-novative and accute methods of assessing and treating nonpoint source water quality problems. The Agricul-tural Engineering Department at Purdue University has been working on the problem of quantifying and treating nonpoint source water quality problems, in conjunction with several local, state and national agencies, since 1972. Water quality problems and their solutions cannot be fully described and understood from monitoring studies alone, due to the spatial and temporal nature of the pro-blem. On the other hand, unverified or unvalidated simulation studies are just as questionable. A methodology is presented which uses both monitoring and modeling information to describe and understand the complex processes of nonpoint source hydrology and pollution production. Examples of the use of the ANSWERS watersehd model in both planning and evaluation applications are provided. The planning example examines a primarily agricultural watershed of approximately 1964 ha both before and after application of several different manage-ment schemes. Selection criteria based both on sediment yield reduction and cost/benefit ratios are presented. The evaluation example utilizes the entire Black Creek watershed in northeastern Indiana in showing the im-pacts of incorporating several types of Best Management Practices (BMPs) throughout the watershed from 1975 to 1978. Spatial as well as temporal changes are noted.