Land and Watershed Management - Practices of Irrigation and On-farm Water Management - page 202

6.4.3.4 Indigenous Vegetation and Wildlife Habitats
Faced with vegetated or natural sites, the designer should advocate use of native
plant species; as the animals that inhabit or depends on a site's natural features.
6.4.3.5 Existing Regulatory Context
In addition to other factors, the existing ordinance and regulations (of the
State/Province) governing land use, site development, construction and conserva-
tion must be considered for land development and planning, water development,
drainage, etc.
6.4.3.6 Sustainability Issues
Engineers and architects should concern with the sustainability issues of the
resources and environments of the surroundings the land to be developed and
graded.
All grading work for drainage or irrigation should be planned as an integral part
of an overall farm system to conserve soil and water resources. Boundaries, eleva-
tions and direction of slope of individual field grading jobs should be such that the
requirements of all adjacent areas in the farm unit can be met. Designs for the area
being graded should include plans for removing excess irrigation and storm runoff
water from the fields.
6.4.3.7 Proposed Plan of Use
The finished degree of smoothness or slope depends on the irrigation method, crop-
ping, anticipated depth to the water table and water quality. As the slope or gradient
increases, less precise grading is needed.
6.4.3.8 Field Size
Under certain circumstances (especially in a mechanized farming system), the
grading costs are related to the field size. The larger the farm, the lower the
costs. As the farm becomes smaller and irrigation runs shorter; labor requirement
increases, machinery operating cost increases, and the proportion of unproductive
land increases.
6.4.3.9 Cost and Benefit Factors
Volume of earthwork to be needed should be included in estimates of total land
grading costs. Unit costs for grading vary with the depth of cuts, length of haul,
how smooth the surface must be, etc. There is a trade-off between the cost of land
grading and the benefits to be achieved, such as efficient water use. If water use