Use In Dry Season Research Articles

Hydrological impacts of climate change in selected ungauged sub-watersheds of Lake Tana Sub-Basin, Upper Blue Nile Basin, Ethiopia: A regionalization approach

Climate change is a global issue affecting the world's hydrology and water resources. Quantifying climate change impacts on hydrology is important for integrated water resources management. The ungauged watersheds of Lake Tana sub-basin are vital for different habitats and communities where various socio-economic activities such as irrigation, and fishing are carried out. Therefore, assessment of the impact of climate change on this sub basin is critical to settingup an integrated water resource management plan for susitnablity of livelihoods. Climate effect evaluation on ungauged catchments' hydrology using continuous hydrological modeling is difficult with the absence of adequate measured hydro-meteorological data for modeling. This study, thus, used a regionalization approach for ungauged watershed impact assessment and an HBV hydrological model for simulation of flow for different RCP scenarios and time domains. Impacts of climate change on the hydrology of the ungauged sub watersheds namely (Gilgel Abay, Gumara, Megech, and Ribb) were studied using two ensemble GCM driven by one RCM(RCA4) under RCP4.5 and RCP8.5 for the 2040s (2020-2049), and 2070s (2050-2079) time domains. The following results were obtained: Summer rainfall drops for RCP4.5, and increments for RCP8.5 with a decline from March to June. Rainfall decreased under RCP4.5 and RCP8.5 in the spring. It was conclude that increased flow in the dry seasons, provided water for agriculture and other uses while, a decrease flow during the rainy seasons would reduce Lake Tana's storage during the summer. Summer storage is useful for the Tana Belles Hydropower project as it, potentially influences water demand and lake's Navigation depth. In the future these changes will potentially have a severe influence on agricultural production by reducing water supply, thereby calling for the successful implementation of adaptation measures to reduce vulnerability. As the study results revealed that there would be future dry flow decreases and wet flow increases, it is therefore,important that the government, and decision-makers should plan for integrated water resources management activities where for example, wet season flow could be stored for dry season use by providing storage structures.

Modeling Surface Water Availability for Irrigation Development in Mbarali River Sub-Catchment Mbeya, Tanzania

Although Tanzania has a large land suitable for irrigation development, only 4.2% of the arable land which is potential for irrigation has been developed. Mbarali District is characterized by commercial and small-scale irrigation activities for paddy production. Currently, surface water availability for irrigation in Mbarali District is dwindling due to high water demands. Inadequate studies that estimate water availability for irrigation is one of the underlying factors to the lack of irrigation development in many parts of Tanzania including in Mbarali District. This study, therefore, aimed to model surface water availability for irrigation development in Mbarali River sub-catchment Mbeya, Tanzania. The Soil and Water Analysis Tool (SWAT) model and field observations were used to accomplish the study. The model estimates that Mbarali River sub-catchment receives about 631 mm of total mean precipitation annually. About 53% of received precipitation is lost through evapotranspiration, 12% recharged to deep aquifer and the remaining 35% discharged to the stream flow through surface runoff, lateral flow and return flow from unconfined aquifer. Discharge to the steam flow contributes to the total annual means of river discharge ranging from 0 - 10 cubic meters per second at upper catchment to 120 - 140 cubic meters per second at lower catchment. The study recommends that the lower reach of the Mbarali River sub-catchment is potential for irrigation than the upper reach as it has potential river flow that can support irrigation activities. The study also notes the urgent need for water reallocation plan to meet competing water needs in the lower reach of Mbarali River sub-catchment. Moreover, the study addresses the potentiality of irrigation in upper catchment under sustainable water management practices including excavation of small ponds to capture and store surface runoff for dry season use or to supplement irrigation as the rainfall declines.

Fodder bank establishment and management for dry season maintenance of small scale livestock industry: A review

The objective of this study therefore, was to review fodder bank establishment and management for dry season supplementary feeding of livestock. Fodder banking involves fencing, planting, concentrating, storing and reserving of forage legumes in hays and silos to which concentrates, mineral and vitamin premixes are added. In addition, legume trees and shrubs such as Acacia spp, Leucaena leucocephala, Mangifera indica, Musa spp, Cajanus cajan, Tamarindus indica, Stylosanthes guianensis, Centrosema pubescens, Desmodium spp etc. are also good fodder crops which are commonly used. Fodder bank converts the above mentioned crops into supplementary or fall back forage kept in small to large plots for dry season use by aging, ailing, nursing, and lactating and high producing animals. The relatively deep roots of these woody perennials allow them to reach soil nutrients and moisture not available to grasses and herbaceous plants. This characteristic enables these plants to retain fresh foliage into the dry season. The ability of some legumes to fix atmospheric nitrogen makes them protein rich feeds. As with all tree planting activities, fodder bank establishment must be planned to coincide with the rainy season. This ensures high seed emergence, plant survival and establishment. Good site selection is paramount, accompanied with thorough land preparation for excellent establishment of fodder banks. These processes are accomplished by mechanical or chemical means. Methods practiced locally for other high value crops are also often used. The goal is a wider seed-bed, in which plant growth and survival will be maximized.

Patch-scale selection patterns of grazing herbivores in the central basalt plains of Kruger National Park

Large herbivores form an essential component in the ecosystem, because of the impact that they have on their surrounding habitat. In this study, we aimed to evaluate some of the mechanisms behind how herbivores select forage at a patch scale. Thirty-six experimental plots were established and fitted with camera traps in Kruger National Park to test forage selectivity by grazers. Plots were manipulated by clearing with a brush cutter and the application of fertiliser. We used generalised linear models to detect trends in probability of occurrence by seven grazing herbivore species using camera trap data. Our results showed that season was a major determinant of species distribution, especially those that are not obligate grazers or feed exclusively in the 0.5 km to 2 km zone from water. We found that most selective feeding occurred in the late wet season when water would be more evenly distributed across the landscape and forage resources close to water would have had the chance to recover from depletion, as a result of dry season use. This has implications for the distribution of artificial water points across the landscape, because areas of reserve forage must be maintained to alleviate grazing pressure close to water.

Sustainable Water Management under Variable Rainfall Conditions in River Communities of Champhone District, Savannakhet Province, Lao PDR

A large majority of the rural population of Lao PDR remains dependent on agriculture for their livelihood and food security, for which access to and management of irrigated and rain-fed water sources is critical. Crop choices and planting calendars follow a monsoonal (dry season/wet season) weather system and are vulnerable to variations in the supply of rainfall, particularly deficits in the dry season and oversupply in the wet season. Climate change projections show that flood vulnerable areas like Champhone district, Savannakhet province might face worse problems in future, affecting food security and agricultural development.This study examines how households are being affected by flooding and drought in Xe Champhone district. Flood vulnerability was assessed by calculating the rainfall variation to determine the water balance during rainy season and dry season. This was combined with analysis of social data from household surveys, together with institutional capacity at different levels and coping strategies currently used by farmers. Constraints and opportunities are identified to strengthen adaptive capacity and resilience to climate change in the Xe Champhone River basin of Savannakhet province. Hydrology data show that the water balance was unstable during both the rainy and dry seasons. The minimum runoff is very low in dry season (Q = 2.4 m³/sec), while the maximum runoff is high in rainy season (Q = 274 m³/sec). Harvesting rainwater in the wet season for use in dry season could reduce the vulnerability of farmers. This study aims to support small-scale community water management initiatives in Lao PDR.

Increased water use in dry season in eight dipterocarp species in a common plantation in the northern boundary of Asian tropics

AbstractThe seasonal water use and stand‐level transpiration of the important tropical timber tree family, Dipterocarpaceae, have not been well investigated. Here, we characterized the seasonal water use and stand‐level transpiration of eight, evergreen, dipterocarps in tropical Southwest China in the 2013 wet and dry seasons: six species grown in monoculture and two species in mixture. We estimated stand‐level transpiration using a power model, combining data from 22 trees of all species measured in the two seasons. Despite significant decreases in soil volumetric water content within 1‐m depth, predawn leaf water potentials (> −0.5 MPa) of all trees indicated access of roots to water. Daily sap flux density (SFDd) of all species closely responded to vapour pressure deficit (VPD). Dry season VPD increased by 29%, compared to in wet season, resulting 27–52% increased SFDd in six of the eight species. Whole tree daily water use was scaled with diameter at 1.3 m height for the 22 trees (r2 = 0.91 and 0.93 in the wet and dry seasons, respectively). Daily mean stand‐level transpiration ranged from 0.63 to 2.23 mm d−1 (mean = 1.05) and from 1.18 to 2.29 mm d−1 (mean = 1.63) in the wet and dry seasons, respectively. Our results reveal conservative water use of dipterocarps and increased transpiration in dry season when a stable soil water source is available. In comparison with introduced fast‐growing timber species, such as Eucalyptus and Acacia mangium, dipterocarp trees and forests consume much less water, making them more suitable as plantation timber crops for the region. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Comparison of soil moisture dynamics between a tropical rain forest and a tropical seasonal forest in Southeast Asia: Impact of seasonal and year‐to‐year variations in rainfall

We examined the impact of both seasonal and year‐to‐year variations in precipitation on simulated soil moisture dynamics at a tropical rain forest (TRF) site and a tropical seasonal forest (TSF) site in Southeast Asia, between which there is a clear difference in the precipitation regime, through a probabilistic ecohydrological model. All model parameters have apparent physical meaning and were obtained by field observations. Rainfall statistics as the primary model forcing terms were constructed from long‐term rainfall records, and their analysis revealed a close relationship between drought and El Niño events at the TRF site and a long‐term drying trend at the TSF site. The model results further demonstrated that the studied ecosystem's robustness (mainly concerning the plant water availability) are attributed to functional factors such as soil texture for the TRF site and rooting depth and the dry season use of water from the preceding wet season for the TSF site.

Dry-season use of space, habitats and shelters by the short-eared rock-wallaby (Petrogale brachyotis) in the monsoon tropics

It is widely recognised that the use of fixed diurnal shelters by rock-wallabies greatly affects their ecology. However, the details of how shelters and surrounding habitats are used, and how similar these characteristics are across rock-wallaby species, remain scarcely understood. The dry season home range, and use of habitats and den sites, of the short-eared rock wallaby (Petrogale brachyotis) were examined at Litchfield National Park, Northern Territory, Australia. We radio-tracked 10 individuals on foot to locate diurnal shelters, and with fixed towers to determine their nocturnal positions. P. brachyotis used a range of rock piles and outcrops for dens, and showed a strong preference for rocky habitats and adjacent woodland. On average, animals used four dens within outcrops, as well as more exposed resting sites. Individual rock-wallabies sometimes shared dens, but there appeared to be male–male intolerance of simultaneous use of dens. Mean home range in the dry season was 18.3 ha, and there was no significant difference in home-range area between sexes. Use of space by P. brachyotis was very similar to that reported for another tropical rock-wallaby species, P. assimilis, and many behavioural traits were also similar to those found in other species of Petrogale.

Refuse to Refuge: Dry Season Use and Modification of Cattle Dung by Subterranean Termites in Guanacaste, Costa Rica1

ABSTRACTBaits and soil cores were used to quantify temporal variation in the use of cattle dung by two species of subterranean termites,Amitermes beaumontiBanks andHoplotermessp. nov. (hereafter referred to by genus), during the 1991 dry season in Guanacaste, Costa Rica. The densities of termite foragers of both species were evaluated in cattle dung patches (baits), in the soil beneath each patch (litter, 0–3.5 cm, and 3.5–7 cm), and in the same layers from adjacent dung‐free control sites. Dung patch and control plots were sampled 3, 10, 60, or 110 days after 1450‐ml dung patches were deposited on the pasture.Amitermesforagers were abundant in 3‐, 10‐, 60‐, and 110‐day‐old dung patch plots with a mean (median) ± SD of 100 (59) ± 120 individuals/bait plot, and only 8 (3) ± 11 individuals/control plot.Hoplotermesforagers were less abundant, with a mean of 22 (0) ± 87 individuals in dung patch plots and 2 (0) ± 9 in control plots.Hoplotermeswas most abundant in the surface litter under 10‐day‐old dung patches, where an average of 39 (0) ± 105 individuals were found. In association with dung patches,Amitermesdensity was highest inside or directly beneath the dung patch and lowest in the 3.5‐ to 7.0‐cm microsite. In control areas, however,Amitermes wasmost abundant in the 3.5‐ to 7.0‐cm microsite.AmitermesandHoplotermeswere found in 35 and 9 of the 54 control plots, respectively. We believe that the high termite densities associated with cattle dung patches can be explained by the energetic and microclimatic requirements of the termites and the physical structure of the dung. Although neither species of termite is a mound builder, these termites use specialized behaviors to exploit and modify dung patches such that foragers have access to concentrated food resources and partial protection from the dry climate and from their invertebrate predators.RESUMESCebos de excremento de vaca y muestras de suelo fueron usados para cuantificar la variación temporal en el uso de excremenco de vaca por dos especies de termitas subterráneas,Amitermes beaumontiBanks yHoplotermessp. nov. (desde aquí referidas por el género), durante la temporada seca de 1991 en Guanacaste, Costa Rica. Se evaluaron las densidades de termitas forrajeras de las dos especies, en los parches de excremento (cebos), en las capas del suelo bajo cada excremento, (superficie, 0‐3.5 cm, y 3.5‐7.0 cm), y en las mismas capas en sitios adyacentes libres de excremento (controles). Tanto los parches de excremento como los controles fueron muestreados 3‐, 10‐, 60‐, o 110‐días después de que los cebos de 1450 ml fueron puestos en el potrero. Los individous forrajeros deAmitermesfueron más abundantes en parcelas de excremento de 3, 10, 60, y 110 días con un promedio (mediana) ± desviacion estandard de 100 (59) ±120 individuos por parcela, mientras las parcelas control tuvieron solo 8 (3) ± 11 individuos por parcela. Individuos forrajeros deHoplotermesfueron menos abundantes con un promedio de 22 (0) ± 87 individuos en las parcelas de excremento y 2 (0) ± 9 en las parcelas control.Hoplotermesfué mas abundantes en la materia orgánica superficial debajo de los parches de excremento de 10 días, donde se encontró un promedio de 39 (0) ± 105 individuos por parcela. En los parches de excremento la densidad deAmitermesfué más alta dentro y directamente debajo de estos y más baja entre 3.5 y 7.0 cm. En los controles, sin embargo,Amitermesfué más abundante en el suelo entre 3.5 y 7.0 cm. Se encontraron individuos deAmitermes y Hoplotermesen 35 y 9 de los 54 sitios controles, respectivamente. Estas altas densidades de termitas asociadas con el excremento de vaca pueden obedecer a los requerimientos energyéticos y microclimaticos de las termitas y la estructura flsica del excremento. A pesar de que ninguna

Refuse to Refuge: Dry Season Use and Modification of Cattle Dung by Subterranean Termites in Guanacaste, Costa Rica1

Baits and soil cores were used to quantify temporal variation in the use of cattle dung by two species of subterranean termites, Amitermes beaumonti Banks and Hoplotermes sp. nov. (hereafter referred to by genus), during the 1991 dry season in Guanacaste, Costa Rica. The densities of termite foragers of both species were evaluated in cattle dung patches (baits), in the soil beneath each patch (litter, 0–3.5 cm, and 3.5–7 cm), and in the same layers from adjacent dung-free control sites. Dung patch and control plots were sampled 3, 10, 60, or 110 days after 1450-ml dung patches were deposited on the pasture. Amitermes foragers were abundant in 3-, 10-, 60-, and 110-day-old dung patch plots with a mean (median) ± SD of 100 (59) ± 120 individuals/bait plot, and only 8 (3) ± 11 individuals/control plot. Hoplotermes foragers were less abundant, with a mean of 22 (0) ± 87 individuals in dung patch plots and 2 (0) ± 9 in control plots. Hoplotermes was most abundant in the surface litter under 10-day-old dung patches, where an average of 39 (0) ± 105 individuals were found. In association with dung patches, Amitermes density was highest inside or directly beneath the dung patch and lowest in the 3.5- to 7.0-cm microsite. In control areas, however, Amitermes was most abundant in the 3.5- to 7.0-cm microsite. Amitermes and Hoplotermes were found in 35 and 9 of the 54 control plots, respectively. We believe that the high termite densities associated with cattle dung patches can be explained by the energetic and microclimatic requirements of the termites and the physical structure of the dung. Although neither species of termite is a mound builder, these termites use specialized behaviors to exploit and modify dung patches such that foragers have access to concentrated food resources and partial protection from the dry climate and from their invertebrate predators.

Transport, storage and mobilization of nitrogen by trees and shrubs in the wet/dry tropics of northern Australia.

Xylem sap from woody species in the wet/dry tropics of northern Australia was analyzed for N compounds. At the peak of the dry season, arginine was the main N compound in sap of most species of woodlands and deciduous monsoon forest. In the wet season, a marked change occurred with amides becoming the main sap N constituents of most species. Species from an evergreen monsoon forest, with a permanent water source, transported amides in the dry season. In the dry season, nitrate accounted for 7 and 12% of total xylem sap N in species of deciduous and evergreen monsoon forests, respectively. In the wet season, the proportion of N present as nitrate increased to 22% in deciduous monsoon forest species. These results suggest that N is taken up and assimilated mainly in the wet season and that this newly assimilated N is mostly transported as amide-N (woodland species, monsoon forest species) and nitrate (monsoon forest species). Arginine is the form in which stored N is remobilized and transported by woodland and deciduous monsoon forest species in the dry season. Several proteins, which may represent bark storage proteins, were detected in inner bark tissue from a range of trees in the dry season, indicating that, although N uptake appears to be limited in the dry season, the many tree and shrub species that produce flowers, fruit or leaves in the dry season use stored N to support growth. Nitrogen characteristics of the studied species are discussed in relation to the tropical environment.