Hydrological Modelling Using Rainfall Simulator over Experimental Hillslope Plot

Abstract

Hydrological processes are complex to compute on hilly areas when compared to the plain areas. Most of the hydrological model do not take into account the critical rainfall-runoff generation processes such as subsurface storm flow, saturation excess flow, overland flow, return flow and pipe storage. The simulations of the above processes in the soil matrix requires detailed hillslope hydrological modelling. In present study, a hillslope experimental plot is designed to study the runoff generation processes on the plot scale. The setup is designed keeping in view the natural hillslope conditions prevailing in the north western Himalayas, India where high intensity storm event occurs frequently. Using the experimental data and the developed conceptual model, the overland flow and the subsurface flow through macropore dominated area has been estimated/analyzed on the pixel basis. Over the experimental hillslope plot, a rainfall simulator was installed to generate the rainfall intensity in the range of 15 to 150 mm/hr which represented the dominating rainfall intensity range in the region. Soil moisture sensors were also installed at 100 mm and 300 mm depth at different locations of the plot to observe soil moisture variations. It was found that once the soil is saturated, it remains in the field capacity for next 24-36 hours. Such antecedent moisture conditions are most favorable for the generation of rapid stormflow from hillslopes. Dye infiltration test was also performed on the undisturbed soil column to observe the macropore fraction variability over the vegetated hillslopes. The surface runoff predicted using the developed hillslope hydrological model compared well with the observed surface runoff under high intensity rainfall conditions.

The increase of rainfall erosivity and initial soil erosion processes due to rainfall acidification

“…The rainfall simulator can be used on rugged terrain as the telescopic legs allow levelling at any slope angle from 0 to 45°. Simulated rainfall is produced with two movable Veejet 80100 nozzles (Blanquies, Scharff, & Hallock, ; Chouksey, Lambey, Nikam, Aggarwal, & Dutta, ; Pall, Dickinson, Beals, & McGirr, ) with a diameter of 4.5 mm. Each nozzle is installed in a metal deposit to collect and reuse the excess of rainfall (that is not sprayed on the plot) and then returned to the pumping system.…”

Farklı Basınçlarda Veejet ve Fulljet Tipi Başlıkların Yağış Şiddeti, Christiansen Katsayısı, Yüzey Akış ve Toprak Kayıpları Üzerine Etkilerinin Kıyaslanması Üzerine Bir Ön Çalışma

“…Toprak kayıpları ise sırasıyla 1.383-2.371 kg m -2 , 0.782-1.643 kg m -2 ve 6.103-6.729 kg m -2 bulunmuştur. Fulljet başlıklarla yapılan bazı çalışmalarında; Arraez et al (2007), yüzey akışları 7.2-41.9 mm saat -1 , toprak kayıplarını 18.2-93.2g m -2 saat -1 , Chouksey et al, (2017), 30 dakika sürede 100 mm saat -1 yağış uygulamışlar ve toplam yüzey akışın yağış şiddetinin % 98'i olduğunu, Shi et al, (2017), yüzey akışları 0.13-0.38 l dakika -1 , toprak kayıplarını ise 3.92-9.02 g l -1 bulmuşlardır. Bu araştırmadan elde edilen bulgularla, diğer araştırma sonuçları arasında da uyumluluk görülmektedir.…”

“…Fulljet tipi başlıklarla yapılan bir araştırmada, konik püskürten Lecher 460.728, 460.608 ve 460.880 tipi başlıklarla 30-117.5 mm saat -1 yağış uygulanmış, yüzey akışlar 7.2-41.9 mm saat -1 ve toprak kayıpları 18.2-93.2g m -2 saat -1 arasında belirlenmiştir (Arraez et al, 2007). Chouksey et al, (2017), dik eğimli arazide hazırladıkları 5x10 m parsellere Fulljet 50WSQ başlıkla 30 dakika sürede 100 mm saat -1 yağış uygulamışlar ve toplam yüzey akışın yağış şiddetinin % 98'i olduğunu belirtmişlerdir. Shi et al, (2017), 1.5x0.75 m boyutlarındaki parsellere Fulljet 35 W başlıkla 2 saat sürede 49.1 mm saat -1 yağış uygulamışlar, yüzey akışların 0.13-0.38 l dakika -1 , toprak kayıplarının ise 3.92-9.02 g l -1 arasında bulmuşlardır.…”

“Cape Fear”—A Hybrid Hillslope Plot for Monitoring Hydrological Processes

“…Micro rain gauges were distributed on the nodes of a 7 × 7 m 2 square grid at the reciprocal distance of 1 m and with the simulator positioned at the center of the square. A similar characterization of a rainfall simulator was conducted by [57]. The diameter of the rain gauges was equal to 68 mm.…”