also covered. Appendices, background, and introductory material aside, the TOD has 8 major sections that correspond to the flowchart in the Programmatic Work Plan (PWP; see Figure 4-1): (1) study design; technical evaluations for (2) hydrology and hydraulics, (3) biology, (4) physical processes, and (5) water quality; (6) integration and interpretation; (7) study report production; and (8) monitoring and validation.

Introduction and Ecological Setting

The TOD opens with two sections, the Introduction and Ecological Setting, that present important background material that introduces the motivation of the Texas instream flow program and necessary components of an instream flow study. In the context of the state mandate to maintain a “sound ecological environment,” the ecological setting of rivers is described. Biology, hydrology and hydraulics, geomorphology, water quality, and connectivity are defined and introduced as the components of an instream flow study.

Study Design

Study Design (Section 3) is a short section that identifies the major steps necessary to begin an instream flow study. Basic steps for starting an instream flow study include compiling and evaluating existing information; identifying stakeholders; identifying appropriate study areas; conducting field reconnaissance, or initial technical assessments; preliminary biological and physical surveys; and the development of geographically-specific objectives and study plans. Without much detail, this section lays out the general approach to design an instream flow study in Texas.

Hydrology and Hydraulics

By far, the Hydrology and Hydraulics section (Section 4) is the most detailed section of the TOD. In it, technical aspects of hydrologic evaluation are discussed, such as historical, naturalized, and environmental flows and flow duration curves. Examples of types of hydrologic models are mentioned. Aspects of hydraulic modeling relevant to instream flow study are major segments, too, including some guidance on how to select a representative reach and methods for data collection. One- and multiple-dimensional modeling options are detailed. Large woody debris is consid-



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