EP 1110-2-9
31 Jul 94
water supply or for drought operation planning. A two-
(a) Flat slopes and wide floodplains could require a
phase planning process (reconnaissance and feasibility)
one- or two-dimensional unsteady flow analysis, resulting
would be followed for reservoir reallocation studies, with
in significant higher study costs compared to using sim-
the HEMP requirements similar to those described in
pler models.
paragraphs 2-3a and b. Drought operation planning is
(b) Major quantitative sedimentation investigations
usually done for an existing project with O&M funding.
may be necessary to firmly establish project feasibility.
A HEMP would be necessary for accurate estimates.
Reservoirs and extensive channel modifications may
require significant quantitative sediment investigations
3-4. Key Items to Evaluate
during the feasibility phase.
a. Major issues. The HEMP must outline the infor-
(c) Physical model testing may be required during
mation and methods necessary to address the major issues
feasibility to ensure the workability of a project, such as
of the hydrologic engineering study. Methods and proce-
locating a replacement lock away from the main naviga-
dures needed to address complex or precedent-setting
tion channel or designing a super-critical flow channel for
problems, sensitive environmental concerns, use of outside
a highly populated area.
consultants (including Corps labs), local sponsor require-
ments, the need for new physical or analytical model
(d) Lake stage-frequency analysis in closed basins,
development, adverse effects caused by a potential pro-
that do not drain to a downstream watershed.
ject, etc., would be scoped for budgeting purposes.
(e) Major groundwater, snow hydrology, water
b. Level of detail. Although the study phase will
quality, or other investigations.
usually establish the overall level of detail, the interdis-
ciplinary planning team must be queried to obtain their
(f) Complex reservoir system problems in which
ideas on the hydrologic information they need. However,
political or environmental issues mandate extensive and
the hydrologic engineering effort often plays the largest
unusual systems modeling.
role in determining the level of detail. Depending on the
appropriate study costs, several iterations between the
(g) Unstable rating relationships, complex interior
hydrologic engineer and the study team may be necessary
flood control studies, multi-reservoir analyses, and other
to establish a level of detail commensurate with the level
difficult water resource analyses must be recognized and
of study funding. The development of a detailed plan,
evaluated during the early planning process leading to a
prepared at the start of the study, should result in a more
HEMP.
efficient and effective progression of the study. Adequate
planning at the start of the study may result in lower
(2) Peer review. Studies having unusual features
overall hydrologic engineering costs.
and complex analyses may benefit from peer review.
HQUSACE has established a peer review procedure
c. Hydrologic information availability and require-
through the HQUSACE-sponsored Hydrology Committee,
ments. Databases would be examined to determine the
with membership consisting of selected senior hydraulic
rainfall, streamflow, topographic, and other records avail-
engineers from Districts and Divisions. The Hydrology
able for the particular study. The need for establishing a
Committee will meet with District personnel to review the
limited data collection program to address the objectives
study/project and offer suggestions on the District's plan
of the study would be determined. Existing Federal and
of analysis. The District incurs no cost for committee
non-Federal projects (reservoirs, levees, water withdraw-
participation. Separate committees on Channel Stabiliza-
als, etc.) affecting the analysis would be determined.
tion, Tidal Hydraulics, and Water Quality are also avail-
able for assistance on unusual features in these areas.
d. Unusual features.
ER 15-2-14 further describes these four committees.
(1) Items requiring additional engineering effort.
Items peculiar to the study area that require additional
between study boundaries and project boundaries in the
hydrologic engineering effort must be addressed, espe-
development of estimates. Project effects often extend far
cially if the work is necessary in the feasibility
upstream and downstream on the main stem of the study
investigation.
3-3
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