Stability of banded vegetation patterns under seasonal rainfall and limited soil moisture storage capacity

2006 ◽  
Vol 29 (10) ◽  
pp. 1556-1564 ◽  
Author(s):  
Nadia Ursino ◽  
Samuel Contarini
2019 ◽  
Vol 11 (21) ◽  
pp. 2580 ◽  
Author(s):  
Yifei Tian ◽  
Lihua Xiong ◽  
Bin Xiong ◽  
Ruodan Zhuang

Integration of satellite-based data with hydrological modelling was generally conducted via data assimilation or model calibration, and both approaches can enhance streamflow predictions. In this study, we assessed the feasibility of another approach that uses satellite-based soil moisture data to directly estimate the parameter β to represent the degree of the spatial distribution of soil moisture storage capacity in the semi-distributed Hymod model. The impact of using historical root-zone soil moisture data from the Soil Moisture Active Passive (SMAP) mission on the prior estimation of the parameter β was explored. Two different ways to incorporate the root-zone soil moisture data to estimate the parameter β are proposed, i.e., one is to derive a priori distribution of β , and the other is to derive a fixed value for β . The simulations of the Hymod models employing the two ways to estimate β are compared with the results produced by the original model, i.e., the one without employing satellite-based data to estimate the parameter β , at three study catchments (the Upper Hanjiang River catchment, the Xiangjiang River catchment, and the Ganjiang River catchment). The results illustrate that the two ways to incorporate the SMAP root-zone soil moisture data in order to predetermine the parameter β of the semi-distributed Hymod model both perform well in simulating streamflow during the calibration period, and a slight improvement was found during the validation period. Notably, deriving a fixed β value from satellite soil moisture data can provide better performance for ungauged catchments despite reducing the model freedom degrees due to fixing the β value. It is concluded that the robustness of the Hymod model in predicting the streamflow can be improved when the spatial information of satellite-based soil moisture data is utilized to estimate the parameter β .


Agriculture ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 44
Author(s):  
Ahmad Numery Ashfaqul Haque ◽  
Md. Kamal Uddin ◽  
Muhammad Firdaus Sulaiman ◽  
Adibah Mohd Amin ◽  
Mahmud Hossain ◽  
...  

Increasing soil moisture storage capacity is a strategy that can be implemented to minimize the use of water in paddy rice cultivation. Organic materials from different sources have the potential to increase soil moisture storage and nutrient enrichment. An incubation study was conducted to evaluate the incorporation of five selected organic amendments—as follows: rice husk biochar (RHB), oil palm empty fruit bunch biochar (EFBB), compost (COMP), rice husk ash (RHA), and oil palm bunch ash (PBA), with a control (no amendment) on soil moisture storage and some chemical properties of soil. The soil was incubated with five amendments for 60 days and sampled at 15-day intervals. After completion of the incubation, a greater extent of gravimetric water content was observed from RHB (0.46 g g−1) and EFBB (0.45 g g−1) followed by compost (0.40 g g−1). The addition of organic amendments significantly influenced soil chemical properties. Maximum soil pH was altered by PBA followed by EFBB compared to its initial value (5.01). The inclusion of EFBB finally contributed to the highest amount of total carbon (7.82%) and nitrogen (0.44%). The addition of PBA showed the highest available P and exchangeable K followed by RHB when compared with the amendments. The results indicated that RHB, EFBB, and compost retain more soil moisture compared to ash sources and added soil nutrients, indicating their potential to improve the chemical and hydrological properties of paddy soil.


2017 ◽  
Vol 8 (3) ◽  
pp. 375-387 ◽  
Author(s):  
Chun Chang ◽  
Ping Feng

Intensified human activities have brought about great changes in runoff generation and convergence. As a significant part of the hydrological process, recession flows represent the capacity of a river basin to store rain and drain it during dry periods; therefore study of the influence of human-induced factors on flood flow recession is of great importance. The Fuping sub-catchment was selected as the study area. Comparisons of land use/land cover and soil moisture storage capacity changes were made between reference and impaired periods. In addition, 64 recession flows during 1958–2005 were simulated using the linear and non-linear reservoir recession models. Then the influence of land use/land cover changes and hydraulic structures on recession flows was identified. Results showed that grassland and cultivated land declined in area while forests increased. At the same time, there was a sharp increase in the soil moisture storage capacity. The non-linear recession model, being more accurate than the linear recession model, was used to simulate the recession process. Compared with recession curves before 1980, the initial outflow from the basin declined while the power law coefficient and recession duration increased; the power law exponent was relatively constant. Furthermore, the shapes of recession curves were flattened.


Water ◽  
2015 ◽  
Vol 7 (12) ◽  
pp. 2691-2706 ◽  
Author(s):  
Weijian Guo ◽  
Chuanhai Wang ◽  
Xianmin Zeng ◽  
Tengfei Ma ◽  
Hai Yang

2016 ◽  
Vol 16 (5) ◽  
pp. 1467-1476 ◽  
Author(s):  
Yong Peng ◽  
Jinggang Chu ◽  
Xinguo Sun ◽  
Huicheng Zhou ◽  
Xiaoli Zhang

Many hydraulic projects such as reservoirs, ponds and paddy fields as well as soil and water conservation engineering projects have been constructed to improve utilization of water resources upstream of the Wudaogou station basin in Northeast China in recent years. As a result, the local hydrological characteristics of the basin and the flood runoff and process have been changed. These changes in the basin characteristics make basin hydrological forecasting more difficult. In order to model and assess this situation, the TOPMODEL, which includes the dynamic soil moisture storage capacity (DSMSC-TOPMODEL), is used in this study to simulate the flood impact of hydraulic projects. Furthermore, the Bayesian method is used to evaluate model parameter uncertainty and assess the TOPMODEL's performance over the basin. Flood simulation results show that accuracy is significantly improved when the stock version of TOPMODEL is replaced with DSMSC-TOPMODEL, with the qualified ratio of forecasting runoff yield increasing from 65% in the former to 88% in the latter. Moreover, these flood simulations are more suitable for helping observers visualize the process.


1957 ◽  
Vol 5 (2) ◽  
pp. 151 ◽  
Author(s):  
RL Specht

Heath vegetation shows a major flush of growth during the mediterraneantype summer season, a time when calculations of the soil moisture storage by the techniques of Thornthwaite (1948) or Prescott, Collins, and Shirpurkar (1952) indicate that severe drought conditions should oocur. Monthly observations on the moisture status of the Makin sand under heath vegetation and, for comparison, under various pastures are therefore recorded. The problems of obtaining an accurate water balance-sheet for such a heterogeneous vegetation as the heath are discussed. Difficulties in the use of the various techniques for measuring soil moisture in sand, which has a low pF of 1.85 at field capacity, are enumerated. The following relationships were found between the evapotranspiration index (Itr = Etr / Ew0.75) and the available water (W). These data were calculated for 6 ft of sand. (i) Heath vegetation (10–14 years old) log (2.4–Itr) = 0.420–0.0383 W (ii) Heath vegetation (burnt) log (2.4–Itr) = 0.461–0.0380 W (iii) Oenothera odorata Jacq. pasture log (2.4–Itr) = 0.395–0.0269 W (iv) Medicago sativa L. pasture log (2.4–Itr) = 0.390–0.0270 W (v) Ehrharta calycina Sm. pasture log (2.4–Itr) = 0.400–0.0339 W From these equations the mean monthly quantities of rainfall which may be stored in 6 ft of sand under the various treatments described were calculated. Drought conditions are shown to occur in December and January, but are relieved in the later months of summer. Even if the stored moisture below 8 ft is considered, the soil moisture status would be expected to be just sufficient to maintain the vegetation in a "dormant" state, and yet the major growth of the heath vegetation occurs at this time. The calculated mean annual values of Itr range from 0.53 to 0.60 for these perennial communities. Close approximations to the actual soil moisture status can be obtained by substituting these values for K in Prescott's formula for potential evaporation, i.e. Etr = K x Ew0.75. Supplementary data on transpiration, growth, and the root systems of the pastures are also included.


1967 ◽  
Vol 69 (1) ◽  
pp. 95-101 ◽  
Author(s):  
W. R. Stern

In a series of five irrigated cotton sowings (T2, T7, T9, T11, T14) evapotranspiration (Et) was determined for the period between October 1961 and October 1962 by observing frequently the changes in soil moisture storage, calculating through drainage, and solving for evapotranspiration in the water balance equation. Thus a water balance was obtained for each sowing extending over the entire crop.The average evapotranspiration in wet season sowings was of the order of 6·5 mm day−1 and in dry season sowings of the order of 4·5 mm day−1. The highest evapotranspiration values ranged between 10 and 12 mm day−1 in T2, T7 and T9 and between 7 and 9·5 mm day−1 in T11 and T14.


2015 ◽  
Vol 3 (1) ◽  
Author(s):  
YENDI FRIADI

ABSTRAK Leachate dapat didefinisikan sebagai cairan yang menginfiltrasi melalui tumpukan sampah dan telah mengekstraksi material terlarut maupun tersuspensi. Sistem instalasi pengolahan leachate bergantung pada debit dan karaktersitik leachate itu sendiri. Tujuan dari penelitian ini adalah memperkirakan debit leachate yang dihasilkan oleh TPA Entikong sebagai acuan dasar perancangan/desain instalasi pengolahan leachate, merencanakan sistem instalasi pengolahan  leachate di TPA Entikong Kabupaten Sanggau serta mengetahui anggaran biaya yang diperlukan dalam perancangan IPL berdasarkan sistem pengolahan yang digunakan.Tahapan untuk mengolah dan menghitung data meliputi perhitungan debit leachate dan mendesain/merancang IPL. Debit leachate dihitung dari rata-rata hujan maksimum bulanan, dari data beberapa tahun atau dengan menggunakan metode neraca air yaitu metode pendekatan Thornhtwaite. Faktor-faktor yang berpengaruh terhadap kuantitas leachate dalam metode neraca air ini adalah presipitasi, evapotransipitasi, surface run-off dan soil moisture storage. Proses desain IPL terdiri dari penentuan letak IPL, penentuan jenis pengolahan, penentuan sistem pengolahan yang ada di Indonesia, pemilihan desain IPL, melakukan perhitungan hidroulik terhadap desain sistem IPL terpilih, menentukan layout bangunan IPL, membuat gambar rancangan, perhitungan anggaran biaya serta membuat spesifikasi teknis pembuatan IPL.Berdasarkan hasil perhitungan menggunakan metode Thornthwaite didapat perkolasi tertinggi sebesar 185,43 mm dan diketahui luas area timbunan sampah TPA Entikong sebesar 1,06 Ha maka diperoleh nilai debit leachate sebesar 65,52 m3/hari. Kandungan organik (BOD) yang terdapat dalam leachate mempunyai nilai BOD sebesar 10.000 mg/L, sehingga metode pengolahan biologi sangat tepat digunakan untuk mengolah leachate di TPA Entikong. Sistem pengolahan yang digunakan adalah pengolahan secara biologi. Unit-unit pengolahan leachate TPA Entikong yang direncanakan adalah bak ekualisasi,  kolam anaerobik, kolam fakultatif, kolam maturasi dan constructed wetland. Besarnya total biaya yang dibutuhkan adalah Rp. 1.375.000.000,00 Kata-kata kunci : BOD, Leachate, Thornthwaite


1982 ◽  
Vol 9 (3) ◽  
pp. 373 ◽  
Author(s):  
GJE Hill

A 2-y study was made of seasonal movement patterns of the eastern grey kangaroo, Macropus giganteus Shaw, in the Warwick district of south-eastern, and the Bollon district of south-western, Queensland. Faecal pellet counts were used to obtain indices of kangaroo usage of cleared country adjacent to cover. Kangaroos were sensitive to changes in forage status, particularly pasture phenology. As quality and quantity of forage reserves declined, animals made progressively greater use of cleared areas. This resulted in marked seasonal changes in distribution patterns. Of the variables quantified (rainfall, soil moisture storage and pasture growth), rainfall provided the best correlations with kangaroo usage of cleared country, explaining 55% (P = 0.002) of the variation in distribution at Warwick and 91% (P = 0.001) of that at Bollon.


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