scholarly journals Impact of Wind on the Spatio-Temporal Variation in Concentration of Suspended Solids in Tonle Sap Lake, Cambodia

Earth ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 424-439
Author(s):  
Michitaka Sato ◽  
Rajendra Khanal ◽  
Sovannara Uk ◽  
Sokly Siev ◽  
Ty Sok ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wind Speed ◽  
Temporal Variation ◽  
Water Depth ◽  
Spatial Interpolation ◽  
Suspended Solids ◽  
High Water ◽  
Tonle Sap Lake ◽  
Tonle Sap ◽  
Spatio Temporal

Even though wind, water depth, and shear stress are important factors governing sediment resuspension in lakes, their actual relations to total suspended solids (TSS) distribution in natural environments have not been well elucidated. This study aims to elucidate the impact of the wind on the spatio-temporal variation of TSS in Tonle Sap Lake, Cambodia, during low-water (March and June, <1 m) and high-water (September and December, 8–10 m) seasons. To this end, wind and TSS data for December 2016 and March, June, and September 2017 were collected and analyzed. For spatial interpolation of wind speed, the inverse distance weighted method was found to be better (R2 = 0.49) than the vectorized average (R2 = 0.30) and inverse of the ratio of distance (R2 = 0.31). Spatial interpolation showed that the wind speed and direction on the lake were <5 m/s and southward during the low-water season and <7 m/s and westward during the high-water season. The TSS concentration in the low-water season was higher (>50 mg/L) than that in the high-water season. The TSS concentration during the low-water season was empirically described by wind speed (W), water depth (D), and shear stress (τ_wave) with a function of W3, W3/D, and exp(W/D) or exp(τ_wave), depending on the location in the lake. The critical shear stress due to wind-induced waves at most of the places in the lake was higher than the total shear stress indicated. Sedimentation was predominant in December and June, and erosion (siltation) was dominant in March. Most of the siltation in March was dominant in the southern part of the lake.

scholarly journals Evolution of Velocity Field and Vortex Structure during Run-Down of Solitary Wave over Very Steep Beach

Water ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1713 ◽  
Author(s):  
Chang Lin ◽  
Wei-Ying Wong ◽  
Ming-Jer Kao ◽  
Ching-Piao Tsai ◽  
Hwung-Hweng Hwung ◽  
...  
Keyword(s):  
Free Surface ◽  
Velocity Field ◽  
Temporal Variation ◽  
Shear Layer ◽  
Froude Number ◽  
Water Depth ◽  
Vortex Structure ◽  
Vortex Core ◽  
Primary Vortex ◽  
Spatio Temporal

An experimental results on the spatio-temporal variation of velocity field and vortex structure, generated from the separated boundary layers on the offshore side of the still-water shoreline, during the run-down process of non-breaking solitary waves over a 1:3 sloping beach are presented. Three waves having the incident wave-height to water-depth ratios (H0/h0) of 0.363, 0.263, and 0.171 were generated in a wave flume. Two flow visualization techniques and high-speed particle image velocimetry were employed. The primary topics and new findings are: (1) Mechanism of the incipient flow separation, accompanied by formation of the separated shear layer from the beach surface, is elucidated under the adverse pressure gradient, using the fine data of velocity measurements very close to the sloping boundary. (2) Occurrence of hydraulic jump subsequently followed by development of the tongue-shaped free surface and projecting jet is demonstrated through spatio-temporal variation in the Froude number. It is confirmed by a change in the Froude number from supercritical to subcritical range as the free surface rapidly rises from the onshore to offshore side. (3) A complete evolution of the primary vortex structure (including the core position, vortex size, and velocity distribution passing through the vortex core) is first introduced systematically, together with the illustration of temporal variation in the topological structure. The non-dimensional shoreward distance of the vortex core section decreases with the increase in the non-dimensional time. However, the non-dimensional size height of the primary vortex increases with increasing non-dimensional time. (4) Two universal similarity profiles for both the wall jet flow and the shear layer flow demonstrate independency of the two similarity profiles of the wave-height to water-depth ratio and the beach slope. The similarity profiles indicate the promising collapse of the data from three previous studies for 1:20, 1:10, and 1:5 sloping beaches.

scholarly journals Spatio-temporal variation of reference evapotranspiration from empirical methods in Chihuahua, Mexico

2021 ◽  
Vol 13 (1) ◽  
pp. 95-115
Author(s):  
Augusto Omar Villa-Camacho ◽  
◽  
Ronald Ernesto Ontiveros-Capurata ◽  
Osías Ruíz-Álvarez ◽  
Alberto González-Sánchez ◽  
...  
Keyword(s):  
Temporal Variation ◽  
Spatial Interpolation ◽  
Reference Evapotranspiration ◽  
Interpolation Method ◽  
Meteorological Data ◽  
Estimation Methods ◽  
Empirical Methods ◽  
Spatio Temporal ◽  
Spatial Interpolation Method ◽  
High Elevations

<strong>Introduction:</strong> Evapotranspiration is key in the management of arid agricultural areas. In Chihuahua, the volume of irrigation water is based on reference evapotranspiration (ET<sub>o</sub>) calculated with empirical methods and extrapolated to the cropped area, which is inaccurate. The alternative is to calculate ET<sub>o</sub> variation by spatial interpolation.</br> <strong>Objective:</strong> To analyze the spatio-temporal variation of ET<sub>o</sub> using empirical methods and spatial interpolation in Chihuahua, Mexico.</br> <strong>Methodology:</strong> Records from 33 meteorological stations from 1960-2013 and seven ET<sub>o</sub> estimation methods were used. The results were compared with the Penman-Monteith method, modified by FAO (PMMF), ANOVA analysis (P ≤ 0.05), and homogeneous ET<sub>o</sub> surfaces built from the point values by spatial interpolation.</br> <strong>Results:</strong> The Hargreaves method (R<sup>2</sup> = 0.91, RMSE = 1.16 and ME = -0.69 mm-day<sup>-1</sup>) had a smaller bias with respect to PMMF. ET<sub>o</sub> values ranged from 2.5 to 7.1 mm-day<sup>-1</sup> in a west-east direction, with maximum values at low elevations and minimum values at high elevations, which showed the influence of the Sierra Madre Occidental on ET<sub>o</sub>. This characteristic was most noticeable in the warm months (June to September).</br> <strong>Limitations of the study:</strong> The use of estimated data needs field validation.</br> <strong>Originality:</strong> The ET<sub>o</sub> estimation with seven empirical methods and one spatial interpolation method to extrapolate values to areas with scarce meteorological data.</br> <strong>Conclusions:</strong> The Hargreaves method allows estimating the spatio-temporal variation of ET<sub>o</sub> in large extensions and areas with limited meteorological information.</br>

Spatio-temporal Variation Characteristics of Surface Net Radiation in China over the Past 50 Years

2013 ◽  
Vol 15 (1) ◽  
pp. 1 ◽  
Author(s):  
Yangzi GAO ◽  
Honglin HE ◽  
Li ZHANG ◽  
Qianqian LU ◽  
Guirui YU ◽  
...  
Keyword(s):  
Temporal Variation ◽  
Net Radiation ◽  
The Past ◽  
Variation Characteristics ◽  
Spatio Temporal

Evaluation of nutrient runoff from the kako river by continuous daily sampling

1996 ◽  
Vol 34 (12) ◽  
pp. 67-72
Author(s):  
Yukio Komai
Keyword(s):  
Suspended Solids ◽  
Water Discharge ◽  
Electronic Conductivity ◽  
High Water ◽  
Nutrient Loads ◽  
Discharge Condition ◽  
Nutrient Runoff ◽  
Average Value ◽  
Daily Sampling ◽  
A Site

A water sample was taken once a day for 15 months at a site near an estuary of the Kako River, Japan, to estimate nutrient loads from rivers to the sea. Total phosphorus (T-P), total nitrogen (T-N), suspended solids (SS) and electronic conductivity (EC) were measured. T-P and SS concentrations varied in proportion to the discharge, and T-P concentrations increased with those of SS, too. EC varied inversely with the discharge, but the fluctuations of T-N concentrations were less than those of T-P and SS concentrations. Water quality remained, for the most part, constant throughout the day. T-P, T-N and SS load were 181t/year, 2320t/year and 51000t/year in 1992, respectively, 54% of T-P load, 47% of T-N load and 80% of SS loads outflowed in those cases where the discharge was more than 100 m3/s, which were 36 days in 1992. 79% of T-P load, 69% of T-N load and 92% of SS load outflowed in periods of high water discharge, which were 88 in 1992. T-P and T-N loads calculated by using one day's data in every month were 151t/year and 2450t/year. But nutrient loads calculated by using the average value of data from an ordinary discharge were two or three times lower than calculated yearly loads. These results showed the importance of estimating the yearly load considering the discharge condition and sampling at a time of high water discharge.

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