Moment Analysis for Modeling Soil Water Distribution in Furrow Irrigation: Variable vs. Constant Ponding Depths

Despite increasing use of pressurized irrigation methods, most irrigation projects worldwide still involve surface systems. Accurate estimation of the amount of infiltrating water and its spatial distribution in the soil is of great importance in the design and management of furrow irrigation systems. Moment analysis has previously been applied to describe the subsurface water distribution using input data from numerical simulations rather than field measured data, and assuming a constant ponding depth in the furrow. A field experiment was conducted in a blocked-end level furrow at Maricopa Agricultural Center, Arizona, USA, to study the effect of time-variable ponding depths on soil water distribution and the resulting wetting bulb under real conditions in the field using moment analysis. The simulated volumetric soil water contents run with variable and constant (average) ponding depths using HYDRUS 2D/3D were almost identical, and both compared favorably with the field data. Hence, only the simulated soil water contents with variable ponding depths were used to calculate the moments. It was concluded that the fluctuating flow depth had no significant influence on the resulting time-evolving ellipses. This was related to the negligible 10-cm variation in ponding depths compared to the high negative matric potential of the unsaturated soil.

Proper Border Length Can Improve Soil Water Distribution, Promote Grain Yield of Winter Wheat, and Potentially Save Water Resources

With water resources becoming scarcer and a growing demand for increased food supplies, there is an urgent need to maximize the efficiency of irrigation systems. We aimed to find a suitable border length to reduce the quantity of irrigation water through a traditional border irrigation system and, thus, alleviate groundwater depletion in Huang-Huai-Hai Plain (3HP). A 2-year experiment (2017–2019) was conducted in 3HP, which three border lengths were tested: 15 m (L15), 25 m (L25), and 35 m (L35); supplementary irrigation was implemented during jointing and anthesis, inflow cutoff was set at 90%, and set a control treatment without irrigation (CK). The results showed that L25 significantly improved soil water distribution after irrigation, and increased soil water consumption compared with L15 and L35. The the dry matter accumulation post-anthesis was also higher in L25 than in the other treatments, as well as the WUE. The correlation analysis of soil water content after irrigation with yield confirmed that L25 was more conducive to high grain yield. Hence, under these test conditions, the irrigation field treatments with a border length of 25 m were considered the most efficient, given that these allow the reduction of the amount of water necessary for irrigation without compromising grain yield of winter wheat.

Infiltration and Soil Water Distribution in Irrigation Furrows Treated with Polyacrylamide

HighlightsControl furrows with 1× inflow rates were compared with 3× advance inflows treated with 10 mg L-1 polymer (WSPAM).WSPAM reduced sediment loads in furrow streams by 89%, despite its 3× greater advance inflows.WSPAM furrow advance times and infiltrated volumes were greater than predicted from increased inflows alone.WSPAM enabled reduced upper-section infiltration and increased lower-section infiltration relative to control furrows.Abstract. Few if any studies have measured the effects of water-soluble anionic polyacrylamide (WSPAM) on infiltration and soil water distribution in different segments of irrigation furrows. We conducted a four-year study on a silt loam soil with 1.5% slopes. Control furrows received no WSPAM and inflows were 15.1 L min-1, whereas WSPAM was applied using 10 mg L-1 a.i. to 45 L min-1 inflows during furrow advance. Despite its greater advance phase inflow rates, WSPAM application reduced sediment concentrations in furrow streams by an average of 89% relative to the control. A surface irrigation model, WinSRFR 5.1, was used to separate furrow inflow rate effects on infiltration from that of WSPAM. Relative to results predicted by simulation for the entire furrow, the polymer treatment: (1) increased advance time an average 1.4-fold, (2) increased advance-phase infiltrated volume 1.5-fold, and (3) increased infiltration volume at the common opportunity time 1.2-fold. Hence, these effects resulted from WSPAM and not from differences in treatment inflow rates. Treatment infiltration amounts varied markedly among irrigations and years, as did the intensity of WSPAM effects. These were attributed mainly to differences in infiltration opportunity time, but temporal differences in soil water content during furrow formation, irrigation water electrical conductivity, initial soil surface water content and water temperature, and the irrigation-long, furrow-stream mean sediment content also appear to have influenced infiltration rates. Although inconsistent, WSPAM increased net furrow infiltration in the lower section and reduced infiltration in the upper section relative to control furrows. This effect could not be explained by the greater inflow rate and shorter advance time of the WSPAM treatments and was attributed to spatially variable WSPAM effects on infiltration opportunity time and possibly irrigation water viscosity. The WSPAM management approach, while protecting against furrow erosion, may potentially provide a means of improving irrigation uniformity and reducing associated percolation water and nutrient losses. Keywords: Furrow advance, Irrigation, Irrigation uniformity, Polymers.

INVESTIGASI ZONA AKUIFER MENGGUNAKAN METODE GEOLISTRIK KONFIGURASI SCHLUMBERGER DI PANTAI PARANGLUHU KECAMATAN BONTOBAHARI, KABUPATEN BULUKUMBA

Water is a natural resource that is essential for needs of living things, especially human beings. Most groundwater widely utilized because the standards compliance of clean water and proper use. However there is a difference in the conditions and quality of the groundwater in different areas, one of which on the territory of coastal zone that can store brackish ground water – salty. This is a lot going on in various parts of the territory of one of the coastal zone subdistrict of Bontobahari. Related conditions, this research was conducted with the aim to find out the characteristics of the aquifer and the salty soil water distribution in the region of coastal zone subdistrict of Bontobahari, Bulukumba. The methods used in this research is the geoelectric resistivity injection using the Schlumberger configuration. Based on the measurement and data processing, resisvity values of aquifer have about 29,4 – 36,1 Ωm and it can be found at a depth of 6,50 – 19,7 m.

Gap thinning improves soil water content, changes the vertical water distribution, and decreases the fluctuation

Although it is clear that gap thinning significantly increases the soil water content (SWC) of the topsoil, less is known about whether and how this treatment affects deeper layers. From December 2008 to April 2012, we monitored the SWC at depths of 10, 20, 30, 45, 60, and 90 cm in gap creation treatments (small gap size of 30 m2, intermediate gap size of 80 m2, and unthinned plots) in a typical pine plantation in the eastern Tibetan Plateau. Among gap treatments, differences in SWC and its coefficient of variation (CV) at each depth and the soil water content proportion (SWCP) of the whole soil profile at specific depths were compared. Gap thinning improved SWC and decreased the CV at each depth. The SWCPs in thinned plots were lower at depths from 10 to 30 cm compared with unthinned plots but higher at depths of 45 and 60 cm. Also, in each season, the patterns were similar to the general results. In conclusion, gap thinning improves the SWC, changes the vertical soil water distribution, and decreases the SWC heterogeneity. The soil water conditions in intermediate gaps are more appropriate for local forest restoration.