ANSWERS: A Model for Watershed Planning

TLDR

Recent years have seen a heightened focus on protecting national water resources, with government, industry, and private stakeholders seeking data on how land use, management, and conservation practices affect watershed water quality and quantity. The report introduces ANSWERS, a watershed simulation tool designed to provide agricultural stakeholders with spatially and temporally resolved data on how land use and management affect water quality, and demonstrates its planning utility through alternative management simulations. ANSWERs integrates a distributed hydrologic model, sediment detachment/transport module, and routing components for overland, subsurface, and channel flows, operating on event‑based rather than long‑term scales. Its event‑oriented, distributed approach enables users to physically describe watershed processes in space and time, improving understanding of hydrologic‑water quality interactions and demonstrating planning value through simulated management alternatives.

Abstract

ABSTRACT IN recent years, a greatly increased emphasis has been placed on improving and maintaining the quality of our national water resources. Agencies and individuals from the various levels of government, industry and private life are seeking information concerning the ef-fects that land use, management, and conservation prac-tices or structures might have on the quality and quantity of water from both agricultural and non-agricultural watersheds. ANSWERS (Areal Nonpoint Source Watershed En-vironment Response Simulation) was developed in an ef-fort to supply the desired information described above for primarily agricultural watersheds. The overall struc-ture consists of a hydrologic model, a sediment detachment/transport model and several routing com-ponents necessary to describe the movement of water in overland, subsurface and channel flow phases. ANSWERS, unlike many large-scale watershed model structures, uses distributed (rather than lumped) parameters and is event (rather than long-term) oriented. These operational features generally yield a better understanding of the hydrologic and water quality interactions involved in a watershed by allowing the user to physically describe those processes both spatially and temporally. The purpose of this report is to present the operational concepts, the basic mathematical model used in ANSWERS, general data needs and user considerations. In addition, the potential utility of ANSWERS as a plan-ning tool is demonstrated by simulating several manage-ment alternatives for a primarily agricultural watershed in northeastern Indiana subjected to several different precipitation events.