Hydrologic Analysis. This effort includes updating prior planning studies and developing new hydrologic analysis to reflect current conditions in the County. Detailed hydrology will be conducted within 1,380 square miles in Williamson County supplemented with leverage hydrology totaling 1,110 square miles beyond the County boundary. Milam County will be conducting hydrology on 320 square miles to complete hydrologic analysison the remainder of the HUC-10 watersheds. Williamson County hydrologic analysis shall include evaluationof the existing condition 2-, 10-, 25-, 50-, 100-, and 500- year frequency events using the latest version of HEC-HMS. Specific tasks include:
Hydrologic Analysis a. The Engineer shall create a hydrologic analysis using HEC-Hydrologic Modeling System (HEC- HMS) if watershed or area of interest is larger than 200 acres. The Engineer shall review and comment on the hydrologic analyses of said analysis and portions of the Project; and
Hydrologic Analysis. Developer shall design the drainage system to accommodate the ultimate development of the drainage areas. Flood damage potential for the completed Project shall not exceed pre-Project conditions.
Hydrologic Analysis. 3.1 Delineate subwatersheds and assign runoff parameters throughout the Drainage Basin sufficient to analyze flows draining to key hydraulic structure locations and large branches throughout the watershed within the “Detailed H&H Analysis” area shown in Figure A-1. The runoff parameters will meet City IDCM standards but also account for the results found in the recent Xxxxxx/Robbinsdale/South Canyon LOMR.
Hydrologic Analysis. The Engineer shall conduct a hydrologic analysis for approximately 12.5 miles of roadway. The analysis shall be completed for three conditions: the pre-2012 construction condition, current conditions (post 2012) and the ultimate conditions. Specific scope of work includes the following: • Pre-2012 Construction Condition
Hydrologic Analysis. For example, a calibrated, continuous-simulation model must be used to estimate runoff in western Washington for flow control best management practices (BMPs). In the case of infiltration facilities, the output from this runoff analysis is combined with estimates of infiltration rates to select the size and geometry of the infiltration facilities. This is described on page 141 of Volume III (included in Appendix A of this report): "The analysis must demonstrate that the BMP will completely infiltrate the design storm within 24 hours (or 48 hours for the 100-year event). If this is not the case, the surface area of the BMP will have to be increased." The recommended approach for sizing infiltration facilities is summarized in Section 2.3.8, pages 140-142 in Volume III of the Washington Department of Ecology draft manual (WDOE, 1999a). The approach is based on using Xxxxx'x law for saturated ground flow, assuming constant hydraulic conductivity and constant gradient. Although the manual points out that "Xxxxx'x Law is difficult to apply to unsaturated flow conditions," it does not suggest other approaches or analytical tools for estimating infiltration rates. In most cases, the uncertainties in estimates of infiltration rates will be significant. It would not be uncommon for the actual, long-term infiltration rate to differ from the estimated infiltration rate by factors of 2 to 10. These differences are primarily due to uncertainties in hydraulic conductivity and hydraulic gradients and because of errors in using the saturated flow equations presented on page 140 to describe infiltration. In the case of infiltration facilities, it not clear that the resources and efforts that are required to estimate surface runoff are justified, given uncertainties inherent in infiltration rate estimates. Or, from another viewpoint, it is not clear that the simplified approach recommended for sizing infiltration systems is justified given the requirements for estimating runoff. It may be appropriate in at least some cases to shift the emphasis to developing better estimates of infiltration rates. This could be accomplished with more sophisticated analytical tools for describing the infiltration process (including computer models) and with more reliable estimates of site characteristics. For example, analytical approaches for estimating infiltration rates from impoundments are presented by XxXxxxxxx and Xxxxxx (1979). The Green-Ampt approximation to Xxxxxxx's equation may a...
Hydrologic Analysis. Sufficient base line data shall be established prior to conducting any surface disturbing activity which shall be determined necessary by the AO. In order to accomplish this, the lessee shall submit for review and approval by the AO a plan to analyze ground and surface water interactions as part of any operations or exploration on the leases. The plan shall be submitted prior to or concurrent with a Mining or Exploration plan under 43 CFR 3592.1. The plan shall include, but not be limited to the following items, and shall describe how the lessee proposes to; (1) develop sufficient baseline groundwater information to document existing hydrogeology associated with Xxxxxx Lake basin fill and underlying carbonates, encompassing a reasonable area of potential resources, springs, and the alluvial and bedrock aquifers. This shall include items such as the location, size, and depth of any hole that will encounter water and/or brine as well as any information that will be collected on each hole. (2) Determine the potential impacts to existing water right holders, xxxxx, wetlands, and surface and groundwater throughout their operations. Water chemistry (including stable isotopes as necessary), estimated flow and water quantity (water balance) shall be addressed. (3) Monitor the actual impacts to groundwater resources throughout and surrounding the operation including but not limited to changes in meteoric precipitation and springs, xxxxx (base conditions, water levels, and chemistry conditions prior to construction and monitoring after construction), wetlands, and ditches. Xxxxx, wetlands, and springs (at sites determined to be relevant based upon the groundwater study that would be conducted prior to development) shall be monitored during operations in order to minimize potential impacts to groundwater resources by allowing an early identification. Further, the plan shall contain sufficient detail to allow it to be independently assessed, and include such things as the type of groundwater model that would be used (and/or other methods of analysis), phasing of the analysis and proposed iterative studies. The plan shall also contain a list of people and their qualifications to accomplish the work and a list of deliverables with a timing schedule. The lessee shall be responsible for any cost incurred for the plan and the accomplishing of the work.
Hydrologic Analysis. A hydrologic analysis of the contributory watershed to develop peak flow rates for analysis in the hydraulic model will be prepared. The watershed and subcatchments will be delineated based on StreamStats watershed delineations, Geographic Information Systems (GIS) / MA DEP LiDAR topographic information, and limited field verification as needed. The watershed will include the entire Xxxxxxx Xxxxx watershed with subcatchments broken out for the major tributaries. Hydrologic analyses will be based on rainfall data from NOAA Atlas 14, as well as projected precipitation amounts modified to reflect climate change impacts, in accordance with data available from xxx.xxxxxxxxxxx.xxx or other sources, such as MassDOT Climate Projection Viewer.
Hydrologic Analysis. ▪ Develop the design flows using StreamStats. ▪ Verify StreamStats basin delineation utilizing available Lidar. ▪ Check StreamStats flows against any nearby gage data and a ratio of the drainage basins. ▪ Calculation of peak discharges for the 2-year through 500-year floods as well as any flows necessary for meeting fish passage requirements.
Hydrologic Analysis. 1. Prepare Drainage Area Maps and determine sub-drainage areas.
