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Controlled Drainage (controlled + drainage)

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Engineering100%

Selected Abstracts

EFFECTS OF CONTROLLED DRAINAGE ON STORM EVENT HYDROLOGY IN A LOBLOLLY PINE PLANTATION,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 1 2000
D. M. Amatya
ABSTRACT: A paired watershed approach was utilized to study the effects of three water management regimes on storm event hydrology in three experimental watersheds in a drained loblolly pine (Pinus taeda L.) plantation in eastern North Carolina. The regimes were: (1) conventional drainage, (2) controlled drainage (CD) to reduce outflows during spring fish recruitment, and (3) controlled drainage to reduce outflows and conserve water during the growing season. Data from two pit-treatment years and three years of CD treatment with raised weirs at the watershed outlet are presented. CD treatment resulted in rises in water table elevations during the summer. But the rises were small and short-lived due to increased evapotranspiration (ET) rates as compared to the spring treatment with lower ET demands. CD treatment had no effect on water tables deeper than 1.3 m. CD treatments, however, significantly (,= 0.05) reduced the stoning outflows for all events, and peak outflow rates for most of the events depending upon the outlet weir level. In some events, flows did not occur at all in watersheds with CD. When event outflows occurred, duration of the event was sharply reduced because of reduced effective ditch depth. Water table depth at the start of an event influenced the effect of CD treatment on storm event hydrology. [source]

Controlled drainage effects on water quality under semi-arid conditions in the western delta of Egypt

IRRIGATION AND DRAINAGE, Issue 4 2001
M.A.S. Wahba
le drainage contrôlé; le drainage conventionnel; la gestion de la liste de l'eau; la qualité de l'eau de drainage Abstract Field experiments were conducted for two years in the Western Delta of Egypt to investigate the effects of controlled drainage on the quality of subsurface drainage outflows. Two water table management methods were applied in the 2.54 ha experimental field: free conventional subsurface drainage and controlled drainage. Controlled drainage was applied at 60 cm depth during both seasons. Drain discharge volumes and nitrate-N and orthophosphate-phosphorus concentrations were monitored during the growing seasons. The controlled drainage (CD) treatment significantly reduced the total drainage outflow by 68% during the summer season and by 28% during the winter of 1999,2000 at 99% confidence level, compared to free conventional drainage (FD) treatment. The CD also reduced the total nitrate-N in drainage water by 73%, and 32% during the summer and the winter seasons respectively, compared to the FD treatment. The CD treatment reduced the total orthophosphate-phosphorus losses by 77% during summer of 1999 and by 30% during winter of 1999,2000 compared to the FD treatment; however, in general the total mass loss was low in both treatments. The results of the experiment showed the potential environmental and economic benefits with the application of controlled drainage in semi-arid regions. Copyright © 2001 John Wiley & Sons, Ltd. Les expériences sur les domaines étaient dirigées pour deux ans dans le delta de l'ouest de l'Egypte, pour étudier les effets du drainage contrôlé sur la qualité de l'écoulement du drainage sous-surface. Deux méthodes du direction de table de l'eau ont été appliquées sur environ 2.54 ha domaines d'expériences, du drainage conventionnel sous-surface libre, et du drainage contrôlé. Le drainage contrôlé était appliqué a 60 cm de profondeur durant les deux saisons, les concentrations des volumes du drain déchargé et du nitrate-N, et les orthophosphate-phosphours étaient surveillées durant les saisons nouvelles. Le drainage contrôlé (DC) traitement a diminué considérablement le total de charge du drainage par taux de 68% durant l'été et par 28% pendant l'hiver de 1999,2000 par 99%, le niveau de confiance en comparaison au traitement du drainage conventionnel libre (DL). Le drainage contrôlé a diminué le taux total du nitrate-N dans l'eau de drainage par taux de 73% pendant l'été et 32% pendant l'hiver comparé avec le traitement du drainage libre. Le drainage contrôlé du taux total d'orthophosphate-phosphours perdu a diminué par 77% pendant l'été 1999, et 30% pendant l'hiver de 1999,2000 comparé avec le traitement du drainage libre, mais en général la masse totale perdue a diminué. Les résultats ont présenté le potentiel environnemental et les bénéfits économiques de l'application du drainage contrôlé dans les régions semi-arides. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Wetlands with controlled drainage and sub-irrigation systems,modelling of the water balance

HYDROLOGICAL PROCESSES, Issue 14 2007
Ottfried Dietrich
Abstract Over the past centuries, the agricultural use of wetlands in Central Europe has required interference with the natural wetland water balance. Often this has consisted of drainage measures alone. In low-precipitation areas, it has also involved the operation of combined drainage and sub-irrigation systems. Model studies conducted as part of planning processes, or with a view to finding out the impact of changing climate conditions on the water balance of wetlands, must take these facts into account. For this reason, a water balance model has been devised for wetlands whose water balance is governed by water resources management systems. It is based on the WBalMo model system. Special modules were integrated into WBalMo to calculate the water balance of wetland areas (WABI module) and to regulate inflow partitioning within the wetland (REGINF module). When calculating the water balance, the WABI module takes into account precipitation and potential evapotranspiration, groundwater levels below surface, soil types, land-use classes, inflows via the running water system, and data for target water levels. It provides actual evapotranspiration, discharge into the running water system, and groundwater levels in the area. The example of the Spreewald, a major wetland area in north-eastern Germany, was used to design and test the WBalMo Spreewald model. The comparison of measured and calculated water balance parameters of the wetland area confirms the suitability of the model for water balance studies in wetlands with complex water resources management systems. The results reveal the strong influence of water management on the water balance of such areas. The model system has proved to be excellently suited for planning and carrying out water management measures aimed at the sustainable development of wetlands. Furthermore, scenario analyses can be used to assess the impact of global change on the water balance of wetlands. Copyright © 2006 John Wiley & Sons, Ltd. [source]

The role of controlled drainage under drought conditions in an irrigated area in NWFP, Pakistan,

IRRIGATION AND DRAINAGE, Issue 2 2003
Gul Daraz Khan
sécheresse; drainage commandé; eaux souterraines; efficacité d'utilisation de l'eau et rendement Abstract The River Swat is the source of irrigation for the entire irrigation system of Mardan, Nowshera and Charsadda districts. Reductions of water and overdrainage have influenced the yield of major crops. The impact of reduced supply at the inlet from the source, drought conditions and overdrainage from the area have lowered the groundwater to a disastrous level. Thus the present groundwater level cannot contribute to the crops. A subsurface collector at its exit in drainage unit 106 was controlled to raise the watertable. The study area was divided into 10 zones. Each zone was separately assessed to analyze the groundwater impact in response to the controlled technique adopted for mitigating drought in different strategies of the canal operation. The interaction of groundwater level with irrigation depth, crop yield, water use efficiency and water saving were also studied. During the rotational period of the canal, irrigations applied in section II raised the water level by nearly 1 m. The upslope area of section III also needed a large irrigation depth. The groundwater level on the downslopes of the lateral drains in sections I and V was at the design depth of 1.1 m during the rotational strategy, while it decreased only slightly on the upslopes of the lateral drains for the same positions. Because of effective control by the collector, the watertable on the downslopes of the laterals in sections II and III was affected less while in the respective upslope area of section III it dropped more than 2 m. The water levels in section IV (both in the upslope and downslope areas along the laterals) remained very close to the design level. A significant contribution of seepage in the upslope of the collector drain considerably reduced the irrigation depths. During the canal closure period, the watertables in the study area dropped to the limit from 2.3 to 3.25 m. After the reopening of the canal, the watertables in sections II, III and IV were raised from 2.55 to 0.70 m. During this period the water levels near the canal reached the design level. The maximum yield of 6.5 tons ha,1 on the downslopes of the lateral drains in section II was obtained, resulting in maximum water use efficiency of 0.93 kg m,3. However, the minimum yield of 3.5 tons ha,1 on the upslopes of the lateral drains in section I was obtained, resulting in the lowest water use efficiency of 0.35 kg m,3 near the deep surface drain (5 m). The impact of controlled subsurface drainage in zones 2, 3 and 7 resulted in the best maintenance of optimum groundwater level and moisture content. Therefore large amounts of extra irrigation water applied (ranging from 23 to 129% of that actually required) in different zones of the controlled area can be saved for drought conditions. Copyright © 2003 John Wiley & Sons, Ltd. RÉSUMÉ Le fleuve Swat est la source d'irrigation pour les systèmes d'irrigation entiers des zones de Mardan, de Nowshera et de Charsadda. Les réductions de drainage de l'eau et d'excédent ont influencé le rendement de récoltes principales. L'impact de l'approvisionnement réduit à l'admission de la source, des conditions de sécheresse et du drainage d'excédent du secteur ont laissé tomber les eaux souterraines à un niveau désastreux. Ainsi le niveau actuel d'eaux souterraines ne peut pas contribuer aux récoltes. Un collecteur à fleur de terre à sa sortie dans l'unité 106 de drainage a été commandé pour soulever le niveau hydrostatique. Le secteur d'étude a été divisé en dix zones. Chaque zone a été séparément évaluée pour analyser l'impact d'eaux souterraines en réponse à la technique commandée adoptée pour atténuer la sécheresse dans différentes stratégies de l'opération de canal. L'interaction du niveau d'eaux souterraines sur la profondeur d'irrigation, le rendement de récolte, l'efficacité d'utilisation de l'eau et l'économie de l'eau ont été également étudié. Pendant la période de rotation du canal, les irrigations appliquées dans la section II ont élevé le niveau d'eau de presque un mètre. Le secteur demontée de la section III avait besoin d'une grande profondeur d'irrigation. Le niveau d'eaux souterraines des déscentes de la vidange latérale dans les sections I et V était à la profondeur de conception de 1.1 m pendant la stratégie de rotation, tandis qu'il diminuait seulement légèrement aux montée des drains latéraux pour les mêmes positions. En raison de la commande efficace du collecteur, le niveau hydrostatique des déscentes des parties latérales dans les sections II et III a été affecté moins, tandis que dans le secteur respectif demontée de la section III il descentait à plus de deux mètres. Les niveaux d'eau dans la section IV (tous les deux dans les secteurs demontée etde déscentes le long des parties latérales) ont demeuré très près de la conception. La contribution significative de l'infiltration dans lamontee du drain de collecteur a considérablement réduit les profondeurs d'irrigation. Pendant la période de fermeture du canal, les niveaux hydrostatiques dans le secteur d'étude sont descendus la limite de 2.3 à 3.25 m. A la réouverture du canal, les niveaux hydrostatiques dans les sections II, III et IV augmenté de 2.55 à 0.70 m. Pendant cette période les niveaux d'eau près du canal ont atteint celui de la concept. Le rendement maximum de 6.5 tons ha,1 aux déscentes des drains latéraux dans la section II a été obtenu, ayant pour résultat l'efficacité maximum d'utilisation de l'eau de 0.93 kg m,3.Cependant le rendement minimum de 3.5 tons ha,1 aux montées des drains latéraux dans la section a été obtenu, ayant pour résultat la plus basse efficacité d'utilisation de l'eau de 0.35 kg m,3 près du drain extérieur profond (5 m). L'impact du drainage à fleur de terre commandé dans les zones 2, 3 et 7 a maintenu le meillear niveau d'eaux souterraines et le contenu d'humidité optimum. Par conséquent la grande quantité de l'eau supplémentaire d'irrigation celle appliquée (s'étendant de 23 à 129% deréellement requise) dans différentes zones de la zone de contrôle peut être sauvée pour les conditions de sécheresse. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Controlled drainage effects on water quality under semi-arid conditions in the western delta of Egypt

IRRIGATION AND DRAINAGE, Issue 4 2001
M.A.S. Wahba
le drainage contrôlé; le drainage conventionnel; la gestion de la liste de l'eau; la qualité de l'eau de drainage Abstract Field experiments were conducted for two years in the Western Delta of Egypt to investigate the effects of controlled drainage on the quality of subsurface drainage outflows. Two water table management methods were applied in the 2.54 ha experimental field: free conventional subsurface drainage and controlled drainage. Controlled drainage was applied at 60 cm depth during both seasons. Drain discharge volumes and nitrate-N and orthophosphate-phosphorus concentrations were monitored during the growing seasons. The controlled drainage (CD) treatment significantly reduced the total drainage outflow by 68% during the summer season and by 28% during the winter of 1999,2000 at 99% confidence level, compared to free conventional drainage (FD) treatment. The CD also reduced the total nitrate-N in drainage water by 73%, and 32% during the summer and the winter seasons respectively, compared to the FD treatment. The CD treatment reduced the total orthophosphate-phosphorus losses by 77% during summer of 1999 and by 30% during winter of 1999,2000 compared to the FD treatment; however, in general the total mass loss was low in both treatments. The results of the experiment showed the potential environmental and economic benefits with the application of controlled drainage in semi-arid regions. Copyright © 2001 John Wiley & Sons, Ltd. Les expériences sur les domaines étaient dirigées pour deux ans dans le delta de l'ouest de l'Egypte, pour étudier les effets du drainage contrôlé sur la qualité de l'écoulement du drainage sous-surface. Deux méthodes du direction de table de l'eau ont été appliquées sur environ 2.54 ha domaines d'expériences, du drainage conventionnel sous-surface libre, et du drainage contrôlé. Le drainage contrôlé était appliqué a 60 cm de profondeur durant les deux saisons, les concentrations des volumes du drain déchargé et du nitrate-N, et les orthophosphate-phosphours étaient surveillées durant les saisons nouvelles. Le drainage contrôlé (DC) traitement a diminué considérablement le total de charge du drainage par taux de 68% durant l'été et par 28% pendant l'hiver de 1999,2000 par 99%, le niveau de confiance en comparaison au traitement du drainage conventionnel libre (DL). Le drainage contrôlé a diminué le taux total du nitrate-N dans l'eau de drainage par taux de 73% pendant l'été et 32% pendant l'hiver comparé avec le traitement du drainage libre. Le drainage contrôlé du taux total d'orthophosphate-phosphours perdu a diminué par 77% pendant l'été 1999, et 30% pendant l'hiver de 1999,2000 comparé avec le traitement du drainage libre, mais en général la masse totale perdue a diminué. Les résultats ont présenté le potentiel environnemental et les bénéfits économiques de l'application du drainage contrôlé dans les régions semi-arides. Copyright © 2001 John Wiley & Sons, Ltd. [source]

EFFECTS OF CONTROLLED DRAINAGE ON STORM EVENT HYDROLOGY IN A LOBLOLLY PINE PLANTATION,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 1 2000
D. M. Amatya
ABSTRACT: A paired watershed approach was utilized to study the effects of three water management regimes on storm event hydrology in three experimental watersheds in a drained loblolly pine (Pinus taeda L.) plantation in eastern North Carolina. The regimes were: (1) conventional drainage, (2) controlled drainage (CD) to reduce outflows during spring fish recruitment, and (3) controlled drainage to reduce outflows and conserve water during the growing season. Data from two pit-treatment years and three years of CD treatment with raised weirs at the watershed outlet are presented. CD treatment resulted in rises in water table elevations during the summer. But the rises were small and short-lived due to increased evapotranspiration (ET) rates as compared to the spring treatment with lower ET demands. CD treatment had no effect on water tables deeper than 1.3 m. CD treatments, however, significantly (,= 0.05) reduced the stoning outflows for all events, and peak outflow rates for most of the events depending upon the outlet weir level. In some events, flows did not occur at all in watersheds with CD. When event outflows occurred, duration of the event was sharply reduced because of reduced effective ditch depth. Water table depth at the start of an event influenced the effect of CD treatment on storm event hydrology. [source]