Hydrology. Performing hydrologic studies in accordance with the 1986 Orange County Hydrology Manual (OCHM) and its Addendum, or other criteria as specified by the COUNTY and/or DISTRICT. These tasks may include performing hydrography studies and reviewing existing hydrologic data/studies provided by COUNTY and/or DISTRICT. The work shall be performed utilizing AES analysis, HEC-1 software, WMS software, manual hand computations or similar. A-E shall perform such hydrology related work to produce a final hydrology report(s), which includes a summary of hydrologic information, hydrology maps and exhibits, a tabulation of the drainage areas, return frequencies and discharges for the watershed and other related information. The reports shall include a CD/DVD/flash drive or other appropriate digital media containing the entire report(s) in PDF, maps in GIS format, hydrology input and output files and other supporting calculations in digital format. All reports will need to be submitted for review and approval by the Director of OC Public Works or designee. Reviewing hydrology studies submitted to COUNTY and/or DISTRICT for approval as to conformity with the OCHM and its addendum or other criteria specified by the COUNTY and/or DISTRICT. A-E’s work shall include reviewing the data sources used in the submitted study for accuracy and appropriateness, and verifying the accuracy of the aerial mapping, topographic mapping and the hydrology map submitted. A-E shall perform field/site investigations as needed in order to assess the accuracy and validity of the watershed conditions and estimated hydrologic parameters used in the hydrology models in the submitted study. A-E shall review the submitted hydrology models including supporting calculations and analyses for conformity with the OCHM, its addendum and/or other applicable COUNTY and/or DISTRICT criteria. A-E shall prepare a comment letter for COUNTY and/or DISTRICT review and approval, stating the findings with recommendations for correcting problems or inaccuracies.
Hydrology. Hydrology is the primary driver of successful wetland restoration or construction. In wetland restoration, hydrology needs to be re-established, whereas in wetland construction a reliable water source is required to establish hydrology. Include the following information on hydrology in the Proposal: • map(s) or figure(s) depicting the catchment area and drainage pathways of the replacement wetland; • the water source and discharge point for the replacement wetland, including any proposed shallow groundwater and/or surface water connections to existing waterbodies; and • classifications of the water regimes in the normative state (prior to anthropogenic disturbance), current state, and post-replacement state. The water regime refers to the surface water permanence in the deepest part of the wetland in most years, and can be classified as follows (adapted from Xxxxxxxx, et al2): o not flooded (less than 1 week flooded); o temporarily flooded (1 – 4 weeks flooded); o seasonally flooded (5 – 17 weeks flooded);
Hydrology. 9 Government Code § 54950 et seq.
Hydrology. A/E shall conform to the requirements, standards, and guidelines of the Orange County Hydrology Manual, including all Addenda thereto and all references and standards referred to therein.
Hydrology. Each stream reach on the site under consideration for credit generation shall be evaluated as to its flow regime, channel forming discharge, and flooding frequency as appropriate, and, if available, the hydrologic gauge data should be obtained and provided to the IRT;
Hydrology. The hydrology of the Project is affected by two main tributaries that combine to form Xxxxxxxx Creek. They are Xxxxxx Creek upstream of Xxxxxxxx Lake and Xxxxxxxx Creek downstream of Xxxxxxxx Lake and above Mill Pond. Xxxxxx Creek is the primary creek that flows into Xxxxxxxx Lake. Outlet Creek is formed by the outflow from Xxxxxxxx Lake and joins Xxxxxxxx Creek approximately one half mile downstream of the Xxxxxxxx Lake Dam. Xxxxxxxx Creek and Xxxxxx Creek originate at the peaks of Salmo and Monumental Mountains at elevation 6,400 and 5,711 ft, respectively. Xxxxxxxx Creek drains the area east and northeast of Xxxxxxxx Lake and has a total drainage basin area of 70.0 square miles. Xxxxxx Creek drains the area to the south and southeast of Xxxxxxxx Lake and has a total drainage area of 52 square miles. The average annual precipitation over the basin areas is about 40 inches, varying from 30 inches in the valleys to about 50 inches on the ridges.
Hydrology. The project area is well drained both horizontally because of the horizontal valleys, vertical slopes and loamy red volcanic soils which are porous and allow for all infiltration, the ranges are covered by tea zones. Due to this, cases of flooding are not likely to happen. Clearing of vegetation on the steep slopes is strictly discouraged as flush surface runoff is likely to dominate the region. The catchments are constituted by lower Aberdare ranges feeding to the numerous rivers and streams around.
Hydrology. The work to be performed by A/E may include, but shall not be limited to:
Hydrology. Where necessary, the site will be roller chopped at periodic intervals to restore a more natural internal drainage pattern. The road and drainage network will be re-engineered to retain water on the site for longer periods of time, restoring historical hydroperiod and hydrologic processes. Some minor expansion of wetland jurisdictional area may occur. Exhibit A-1-7 shows the locations of the hydrologic work proposed at the BPMB. The activities planned for the site are installation of hardened low water crossings, equalizer culverts, modification of existing drainage culverts and ditches (Exhibit A-1-7). Surface and ground water level data and field-verification that the appropriate elevation has been set will be used to verify the invert elevations at each crossing. If the invert elevations of the structures are found to be too high or low, they will be manipulated based on the field data collection results during the first few years of the project. That data will be used to verify the final elevations for each structure. Those portions of the existing roadway network that will not be used as part of the proposed road and trail network may be leveled out to surrounding grade if necessary to restore the flow patterns, using appropriate erosion control measures to protect the adjacent waters and wetlands.
Hydrology. Develop existing and proposed runoff flows for the 10% (10 year) and 1% (100 year) storm events, at a minimum for each subarea of the watershed for the study area. Provide the appropriate parameters used for the flow calculations, including runoff coefficients, curve numbers (if applicable), time of concentration, percent imperviousness, rainfall intensities and rainfall hyetographs. The project is contained within the Johnson County Indian Creek Watershed study area, and the 1% (100 year) storm event shall be reviewed for conformance with the SMP requirements.
