Laserfiche WebLink
<br />>s not the intent of any level of improvement to modify existing water <br /> <br />rights. Each level of improvement considers the duration, the frequency of <br /> <br />irrigation and the distribution of water across each field as the means for <br /> <br />achieving the recommended improvements. Each level of improvement consists <br /> <br />of a different combination of duration, frequency and distribution. <br /> <br />Levels of System Improvements <br /> <br />Improvements in the irrigation systems consist of (1) ditch lining or <br /> <br />pipelines to reduce seepage losses, (2) water measuring and control struc- <br /> <br />tures and land leveling for control and uniformity in applying water during <br /> <br />each irrigation, (3) subsurface drains for existing open drains to combine <br /> <br />fields into more efficient units, and (4) ditches or ponds to control <br /> <br />surface water leaving the fields. Although subsurface drains also may be <br /> <br />needed to lower existing high water tables that impede cultivation and crop <br /> <br />growth, this practice is not considered applicable for salinity control. <br /> <br />Levels of Improvement <br /> <br />Level One - This level represents a minimum improvement >n existing, <br /> <br />onfann irrigation systems and management practices. Time of set is the <br /> <br />primary change from existing management practice reflected in results of the <br /> <br />irrigation analysis. Using three-hour increments of change and the present <br /> <br />flow rate per furrow the IRMA program derived the time of set needed to <br /> <br />apply the recommended net application during each irrigation. <br /> <br />Elements of structural improvement include ditch lining or pipelines <br /> <br />for field supply ditches, ditch lining and gated p>pes for field head <br /> <br />ditches, constructing earth ditches to control tailwater, land leveling and <br /> <br />closed drains where applicable for each existing field. <br /> <br />Level One can reduce salt loading by 184,000 tons from onfarm ditch <br /> <br />seepage, and by 4,000 tons from tailwater ditch seepage but will increase <br /> <br />salt loading from deep percolation by 46,000 tons. The net 142,000 tons, a <br /> <br />G01213 <br /> <br />11-10 <br />