Проектирование ирригационных и дренажных систем

The study was conducted at the Wondo Genet Agricultural Research Center, Ethiopia, latitude 8°25'59'', longitude 39°01'44''and altitude of 1800 m.a.s.l to determine optimal soil moisture depletion level for lemongrass (Cymbopogon citratus L.). Six level of soil moisture depletion level (20, 30, 40, 50, 60 and 100% of total available water of the soil (TAW) with three replication were used as treatments to evaluate the yield and yield component of lemongrass in randomized complete block design. Different level of soil moisture depletion level significantly (p

According to the 2005 U.S. Geological Survey national water use compilation, irrigation is the second largest use of fresh water in the United States, accounting for 37%, or 484.48 million cubic meters per day, of total freshwater withdrawal. Accurately estimating the amount of water withdrawals and actual consumptive water use (the difference between water withdrawals and return flow) for irrigation at a regional scale is difficult. Remote sensing methods make it possible to compare actual ET (ETa) rates which can serve as a proxy for consumptive water use from different irrigation regimes at a regional scale in a systematic manner. This study investigates crucial components of water use from irrigation such as the difference of ETa rates from flood- and sprinkler-irrigated fields, spatial variability of ETa within a watershed, and the effect of sprinkler irrigation on the water budget of the study area. The mean accumulated ETa depth for the 1,051 square kilometer study area within the upper Smith River watershed was about 467 mm 30-meter per pixel for the 2007 growing season (April through mid-October). The total accumulated volume of ETa for the study area was about 474.705 million cubic meters. The mean accumulated ETa depth from sprinkler-irrigated land was about 687 mm and from flood-irrigated land was about 621 mm from flood-irrigated land. On average, the ETa rate from sprinkler-irrigated fields was 0.25 mm per day higher than flood-irrigated fields over the growing season. Spatial analysis showed that ETa rates within individual fields of a single crop type that are irrigated with a single method (sprinkler or flood) can vary up to about 8 mm per day. It was estimated that the amount of sprinkler irrigation in 2007 accounted for approximately 3% of the total volume of ETa in the study area. When compared to non-irrigated dryland, sprinkler irrigation increases ETa by about 59 to 82% per unit area.

This study was aimed at examining analysing the impact of small scale irrigation on household food security in Sibu Sire district of Western Oromia regional state. Data were collected from 105 irrigation users and 45 non-users. Multi-stage stratified random sampling was applied to select the respondents. Descriptive statistics, Heckman twostage model and Greer and Thorbecke methods were applied to analyse the data. And the analysis research result implies that 44% of the non-users and 27% of users were food insecure. The result was also revealed that 56% of nonusers and 73% of the users were food secured. The model’s first stage revealed the significance effects of distance from the water source, size of cultivated land, access to credit service, access to extension, livestock holding and soil fertility factors in irrigation utilization. The second stage of the model discovered that access to irrigation, household size, dependency ratio, size of cultivated land, proximity of the households to a water source, distance from the market, livestock holding, crop pest infestation, and the Inverse Mills ratio are the determinants of household food security. The study analysis concluded that small scale irrigation utilization is one of the viable solutions to secure household food needs in the study area.