Jack Sieber

WEAP21 - A Demand-, Priority-, and Preference-Driven Water Planning Model Part 1: Model Characteristics

Abstract The Water Evaluation and Planning Version 21 (WEAP21) Integrated Water Resource Management (IWRM) model seamlessly integrates water supplies generated through watershed-scale hydrologic processes with a water management model driven by water demands and environmental requirements and is governed by the natural watershed and physical network of reservoirs, canals, and diversions. This version (WEAP21) extends the previous WEAP model by introducing the concept of demand priorities and supply preferences, which are used in a linear programming heuristic to solve the water allocation problem as an alternative to multi-criteria weighting or rule-based logic approaches. WEAP21 introduces a transparent set of model objects and procedures that can be used to analyze a full range of issues faced by water planners through a scenario-based approach. These issues include climate variability and change, watershed condition, anticipated demands, ecosystem needs, the regulatory environment, operational objectives, and available infrastructure.

WEAP21 -a demand-, priority-, and preference-driven water planning model Part 2 : Aiding freshwater ecosystem service evaluation

Abstract Potential conflicts arising from competing demands of complex water resource systems require a holistic approach to address the tradeoff landscape inherent in freshwater ecosystem service evaluation. The Water Evaluation and Planning model version 21 (WEAP21) is a comprehensive integrated water resource management (IWRM) model that can aid in the evaluation of ecosystem services by integrating natural watershed processes with socio-economic elements that include the infrastructure and institutions that govern the allocation of available freshwater supplies. The bio-physical and socioeconomic components of Battle Creek and Cow Creek, two tributaries of the Sacramento River of Northern California, USA, were used to illustrate how a new hydrologic sub-module in WEAP21 can be used in conjunction with an imbedded water allocation algorithm to simulate the hydrologic response of the watersheds and aid in evaluating freshwater ecosystem service tradeoffs under alternative scenarios.

An Optimization Approach for Balancing Human and Ecological Flow Needs

Balancing human and environmental water resource needs is critical to environmental sustainability. In this paper two concepts are advanced. First, a methodology is introduced to evaluate water management policies and their impacts on the characteristics of both instream flow and water supply reliability. The concept of an “ecodeficit” is introduced to quantify the impact of changes to the natural flow regime resulting from human withdrawals. This metric provides a numerical and graphical representation of the tradeoff between human and ecological needs for available water. Second, we evaluate an approach that involves both simulation and optimization of alternative reservoir release policies. We demonstrate that by refining the quantity and timing of reservoir releases the reliability of a water supply yield can be substantially maintained while improving the satisfaction of ecological flows requirements. These two concepts are early applications of a more comprehensive ecological water supply management approach currently under development.

A water resources model to explore the implications of energy alternatives in the southwestern US

This letter documents the development and validation of a climate-driven, southwestern-US-wide water resources planning model that is being used to explore the implications of extended drought and climate warming on the allocation of water among competing uses. These model uses include a separate accounting for irrigated agriculture; municipal indoor use based on local population and per-capita consumption; climate-driven municipal outdoor turf and amenity watering; and thermoelectric cooling. The model simulates the natural and managed flows of rivers throughout the southwest, including the South Platte, the Arkansas, the Colorado, the Green, the Salt, the Sacramento, the San Joaquin, the Owens, and more than 50 others. Calibration was performed on parameters of land cover, snow accumulation and melt, and water capacity and hydraulic conductivity of soil horizons. Goodness of fit statistics and other measures of performance are shown for a select number of locations and are used to summarize the model’s ability to represent monthly streamflow, reservoir storages, surface and ground water deliveries, etc, under 1980–2010 levels of sectoral water use.