Hydrogeology Journal

, 17:247 | Cite as

The hydrogeological role of trees in water-limited environments

Paper

Abstract

Field experiments have already proven that many tree species in water-limited environments (WLE) depend on groundwater. Typically, such trees survive dry seasons and droughts by uptake of water, directly from the groundwater body or from the capillary fringe, by rooting systems that may extend to several tens of meters depth. Such trees are also very efficient in finding soil moisture in the unsaturated zone, reducing groundwater recharge. Considering that WLE are typically characterized by low recharge, and that trees may use a significant amount of groundwater, this groundwater “consumption” should not be neglected in groundwater balancing, modeling and resources management. In practice, groundwater uptake by trees in WLE is either underestimated or disregarded because of limited knowledge about that phenomenon. This review discusses the current understanding of the hydrogeological role of trees in water-limited environments, the partitioning of tree transpiration into groundwater and unsaturated zone contributions and the integration of that partitioning in numerical groundwater models. Problems involved in this research are highlighted and possible future research directions are discussed.

Keywords

Groundwater transpiration Tree sap flow Stable isotopes Modeling Arid regions 

Le rôle hydrogéologique des arbres dans les milieux environnementaux limités en eau

Résumé

La dépendance par rapport aux eaux souterraines de plusieurs espèces d’arbres en milieux environnementaux limités en eau (MELA) a déjà été prouvée par des expériences de terrain. Typiquement, ces arbres résistent aux saisons sèches et sécheresses en puissant l’eau directement de l’aquifère ou de la frange capillaire par l’intermédiaire de leur système racinaire qui peut atteindre plusieurs dizaines de mètres de profondeur. Ces arbres sont aussi très efficaces pour prélever l’humidité du sol, réduisant ainsi la recharge des aquifères. Vu que les MELA sont caractérisés par une faible recharge et que les arbres peuvent utiliser une quantité d’eau souterraine significative, cette « consommation » d’eau souterraine ne devrait pas être négligée dans le calcul des bilans hydriques, la modélisation et la gestion de la ressource. Dans la pratique, le prélèvement d’eau souterraine par les arbres en MELA est sous estimé ou négligé car les connaissances de ce phénomène sont limitées. Cet article revoit la compréhension actuelle du rôle hydrogéologique des arbres en MELA, la quantification de la contribution des eaux souterraines et de la zone non saturée à la transpiration totale des arbres et l’intégration de ces contributions dans les modèles hydrogéologiques numériques. Les problèmes inhérents à ce type de recherche sont mis en évidence et des axes de recherche future sont proposés.

El rol hidrogeológico de los árboles en ambientes limitados por agua

Resumen

Las experiencias de campo han demostrado que muchas especies de árboles en ambientes limitados por agua (ALA) dependen del agua subterránea. Distintivamente, los árboles sobreviven a estaciones secas y sequías consumiendo agua, directamente del cuerpo de agua subterránea o de su franja capilar, a través de un sistema de raíces que pueden alcanzar varias decenas de metros de profundidad. Los árboles son además muy eficientes en el aprovechamiento de la humedad del suelo en la zona no saturada, reduciendo la recarga del agua subterránea. Considerando que los ALA se caracterizan por su baja recarga y que los árboles pueden utilizar cantidades significativas de agua subterránea, tal consumo de agua no debiera despreciarse en los balances de agua subterránea, en la modelación y en el manejo de los recursos hídricos. En la práctica, el consumo de aguas subterráneas por parte de los árboles en ALA se subestima o no se toma en cuenta debido al limitado conocimiento sobre este fenómeno. Esta revisión trata sobre el conocimiento actual del rol hidrogeológico de los árboles en ambientes limitados por agua; de como discretizar el agua transpirada por los árboles en contribuciones de aguas subterráneas y de la zona no saturada, y la integración de estas contribuciones a modelos numéricos de agua subterránea. Se destacan los problemas relacionados con la dicretización de la transpiración y se discuten las posibles direcciones en futuras investigaciones sobre este tema.

Die hydrologische Bedeutung von Baumbestand in wasserlimitierten Gebieten

Kurzfassung

Feldforschungsexperimente haben belegt, dass viele Baumarten in wasserlimitierten Gebieten vom Grundwasser abhängig sind. Normalerweise überleben derartige Baumarten die Trockenzeit und Dürre durch Aufnahme von Wasser direkt aus der grundwasserführenden Schicht oder aus dem Kapillarsaum mittels eines beträchtlichen Wurzelwerks, das sich über einige duzend Meter Tiefe erstrecken kann. Darüber hinaus sind solche Baumarten auch sehr effektiv im Entziehen von Bodenfeuchtigkeit aus der ungesättigten Zone, was zu einer verminderten Grundwasseranreicherung führt. Wenn man berücksichtigt, dass sich wasserlimitierte Gebiete normalerweise durch eine geringe Grundwasseranreicherung auszeichnen, und dass der Baumbestand einen beträchtlichen Anteil des Grundwassers konsumiert, sollte dieser Grundwasserverbrauch innerhalb der Grundwasserbilanz, -modellierung und der Grundwasserwirtschaft nicht außer Acht gelassen werden. Dennoch wird der Grundwasserverbrauch durch Bäume in wasserlimitierten Gebieten entweder unterschätzt oder nicht berücksichtigt, verursacht durch fehlende Kenntnisse über dieses Phänomen. Diese Rezension gibt einen Überblick über den derzeitigen Kenntnisstand der hydrologischen Bedeutung von Bäumen in wasserlimitierten Gebieten, über die Aufteilung der Baumtranspiration in einen Grundwasseranteil und den der ungesättigten Zone, sowie die Integrierung dieser Anteile in die Grundwassermodellierung. Probleme innerhalb des Forschungsbereiches werden akzentuiert und zukünftige Forschungsrichtungen diskutiert.

الدور الهيدروجيولوجي للأشجار في البيئة الجافة

الدور الهيدروجيولوجي للأشجار في البيئة الجافة

برهنت التجارب الحقلية أنّ أنواع كثيرة من الأ شجار في البيئة الجافة تعتمد في نموها على المياه الجوفيّة. بشكل خاصّ ، تستطيع هذه الأشجارتحمل حالات الجفاف و الجدب عن طريق أخذ المياه مباشرة من المصادر الجوفيّة أو من الهدب الشعريّة أو بواسطة نظام الجذور اللتي يمكن أنّ تمتد في العمق إلى عشرات من الأمتار. هذه الأشجار فعّالة جدّا في الحصول على الرطوبة من التربة في الطبقات غير المشبعة مما يقلّل من عملية الرشح إلى المياه الجوفيّة و بالتالي تخفيض مخزونها. إعتبارا أنّ ميّزة البيئة الجافة هو إنخفاض معدل إعادة الرشح إلى المياه الجوفيّة ، وأنّ الأشجار يمكن أن تمتص مقدار هامّا من المياه ، فإنّ هذا الإستهلاك لا يمكن إهماله في نماذج محاكاة توازن المياه الجوفيّة و إدارة الموارد المائية. عمليا، في النماذج الرياضيّة يتم إهمال كمية المياه الجوفيّة الممتصة بواسطة جذور الأشجار في البيئة الجافة بسبب المعرفة المحدودة حول هذه الظاهرة. هذا البحث يناقش المعلومات المتوافرة حاليّا عن الدور اللذي تلعبه هذه الأشجار في هيدروجيولوجيّة البيئة الجافة و تحديد مساهمة المياه الجوفيّة و طبقات التربة غير المشبعة في تعرق الأشجار و دمج هذه المعطيات في النماذج الرياضيّة للمياه الجوفيّة. نشرح أيضا الصعوبات المتضمّنة في هذا البحث و نناقش بعض البحوث المستقبلية الممكنة في هذا المضمار.

树木在缺水环境下的水文地质学作用

摘要:

很多野外试验已经表明许多树种在缺水环境下主要依赖地下水存活。比较典型的是这些树木能够在干季和干旱季节得以存活, 依靠的就是它们几十米深的根系, 直接从地下水体中或者依靠毛管边缘抽取水分。这些树木在非饱和带寻找地下水, 减少地下水排放方面也是非常高效的。考虑到缺水环境典型的标志是低排放量和树木对地下水的大量利用, 这些地下水的消耗不应该在地下水平衡、模拟以及地下水资源管理中被忽视。实际上, 由于对相关现象缺乏理解, 树木在缺水环境下对地下水资源的抽取利用一直被低估或忽视了。这篇综述讨论了现今对树木在缺水环境下的水文地质作用的理解、树木对地下水和非饱和带的蒸腾作用以及数值水文模式对这种作用的整合。文章强调了这些研究中所存在的问题, 并对将来可能的研究方向进行了讨论。

Hydrogeologické poslání dřevin v oblastech s omeyenými vodními zdroji

Abstrakt

Je již dokázáno, že mnoho druhů dřevin v oblastech s omezenými vodními zdroji závisí od spodních vod. Pro tyto dřeviny je typické, že prožijí období sucha nasátím vody pomocí kořenového systému (dlouhého někdy až desítky metrů) přímo ze zdroja podzemní vody nebo z pásma kapilární třásně. Tyto dřeviny rovněž vynikají schopností vyhledat vlhkost z půdy v nenasycené zóně, snižujíc tak zásoby podzemních vod. Jestli uvážíme, že oblasti s omezenými vodními zdroji jsou charakterizovány sníženou schopností obnovy zásob podzemích vod a že dřeviny mohou spotřebovat významnou čast těchto zásob, tak tyhle fakta by neměli být opomenuty ve vyrovnávání, modelování a manažmentu podzemních vod. V praxi bývá spotřeba podzemních vod dřevinami mnohokrát podceňována, nebo dokonce opomíjená, jenom kvůli omezeným znalostem tohoto fenoménu. Příspěvek se zaoberá hydrogeologickým posláním dřevin v oblastech s omezenými vodními zdroji, štěpením transpirace dřevin do podzemních vod a do půdy v nenasycených zonách, a integrací štěpení v numerických modelech podzemních vod. Příspěvek zvýrazňuje problémy současného a naznačuje směry budoucého výskumu tohoto druhu.

De hydrogeologische rol van bomen in water-gelimiteerde gebieden

Abstract

Veldexperimenten hebben reeds aangetoond dat vele boomsoorten in water-gelimiteerde gebieden (water-limited environments, WLE) afhankelijk zijn van grondwater. Deze bomen overleven tijdens seizoens of langduriger droogte door opname van water vanuit de capillaire zone of direct van het grondwater zelf, met wortelsystemen die een diepte van verscheidene tientallen meters kunnen bereiken. Tevens zijn dergelijke bomen ook efficient in het vinden van bodemvocht in the onverzadigde zone, waardoor de grondwatervoeding afneemt. Typerend voor een WLE is dat de grondwatervoeding gering is en dat de bomen een aanmerkelijke hoeveelheid grondwater kunnen opnemen; deze grondwater “consumptie” moet niet verontachtzaamd worden in de grondwaterbalans, bij het modeleren en het grondwaterbeheer. In de praktijk wordt de grondwateropname in WLE onderschat of verwaarloosd vanwege gebrekkige kennis van het fenomeen. In dit overzichtsartikel wordt besproken de huidige kennis van de hydrogeologische rol van bomen in WLE, de verdeling van transpiratie door bomen vanuit de onverzadigde zone en de verzadigde zone en de integratie van die verdeling in numerieke grondwatermodellen. Onderzoeksproblemen worden belicht en mogelijke richtingen voor toekomstig onderzoek worden besproken.

A fák hidrogeológiai szerepe vízszegény környezetben

Összefoglalás

Terepi mérések bebizonyították, hogy vízszegény környezetben sok fafaj a felszín alatti vízkészletekből táplálkozik. Ezek a fafajok szárazság esetén közvetlenül a felszínalatti víztestekből vagy azok kapilláris rétegéből veszik fel a túlélésükhöz szükséges vizet több tízméterre lenyúló gyökérzetükkel. Ezek a fafajok nagyon hatékonyan tudják kihasználni a telítetlen zóna talajnedvességét is, csökkentve ezzel a beszivárgást. Figyelembe véve, hogy a vízszegény környezetet nagyon kis beszivárgás jellemzi és hogy a fák jelentős vízmennyiséget használnak fel a felszín alatti vizekből, ezt a talajvíz fogyasztást nem lehet elhanyagolni a vízmérleg számítása, modellezése és a vízkészletgazdálkodás során. Az idevonatkozó tudás hézagossága miatt a gyakorlatban, vízszegény területeken alulbecsülik, vagy egyáltalán nem veszik számításba a fák talajvíz felvételét. Ez a tanulmány áttekinti a jelenlegi tudásunkat a fák hidrogeológiai szerepéről vízhiányos környezetben. Tárgyalja a fák transzspiráció forrásának megoszlását a telítetlen zóna és a talajvíz között, valamint, hogy miként lehet ezt a numerikus talajvízmodellekben figyelembe venni. A cikk a kutatás folyamán felmerülő újabb kédéseket és a lehetséges további lépések irányát is felvázolja.

Il ruolo idrogeologico degli alberi in ambienti con scarsita’ d’acqua

Abstract

E dimostrato, da esperimenti in-situ, che molte specie di alberi presenti in ambienti con scarsita’ d’acqua (water-limited enivronments-WLE) dipendono dalla falda sotterranea. In particolare, questo tipo di alberi e’ in grado di sopravvivere alle stagioni secche ed a periodi di siccita’ prolungata prelevando acqua direttamente dalla falda o dalla zona di risalita capillare, utilizzando un sistema di radici in grado di estendersi in profondita’ per parecchie decine di metri. Questi alberi sono anche particolarmente efficenti nell’intercettare l’umidita’ nella zona insatura riducendo la possibilita’ di ricarica della falda. Considerando che i WLE sono ambienti caratterizzati da bassi valori di ricarica e che questi alberi sfruttano una considerevole quantita’ di acque sotterranee, questo utilizzo dell’acqua di falda non dovrebbe essere tralasciato nel bilancio, nella gestione e nel modellamento delle acque sotterranee. Nella pratica l’acqua di falda prelevata dagli alberi in WLE e’ sottostimata o ignorata a causa delle scarse conoscenze riguardo al fenomeno. Questa articolo si propone di descrivere l’attuale livello di conoscenze in campo idrogelogico del ruolo degli alberi in ambienti con scarsita’ d’acqua, la suddivisione del contributo della traspirazione proveniente da zona satura e insatura, e l’integrazione di questa ripartizione nei modelli numerici delle acque sotterranee. Sono messi in evidenza i problemi inerenti questo campo di ricerca e le possibili future linee di ricerca.

نقش هیدروژئولوژیکی درختان در زیستگاههای کم آب

چکیده:

درآزمایشات میدانی ثابت گردیده است که گونه های فراوانی از درختان در مناطق و زیستگاه های با منابع آب محدود یا کم آب متکی به آب زیر زمینی هستند. این درختان، بخصوص در فصل خشک سال و درخشکسالی ها با جذب آب و به طور مستقیم از پیکره آب زیرزمینی و ازطریق لوله های مویین به وسیله ریشه هایی که حتی در اعماق دهها متری می توانند وجود داشته باشند به حیات خود ادامه می دهند. این درختان به طور موثر می توانند از رطوبت موجود در ناحیه غیر اشباع استفاده کرده و تغذیه آب های زیرزمینی را کاهش دهند. حال با توجه به این که در مناطق کم آب تغذیه پایین است و اینکه این گونه درختان از آب زیرزمینی قابل توجهی استفاده می کنند این مصرف آب زیرزمینی می تواند سهم بسزایی در بیلان آب زیرزمینی داشته و نباید از نظر دور بماند. در عمل، جذب آب زیر زمینی توسط این درختان در محیط کم آب اغلب یا کم تخمین زده شده و یا نا چیزشمرده می شود که علت آن عدم آگاهی کامل از این پدیده است. لذا این مقاله شامل بررسی و انعکاس یافته های مربوط به نقش هیدروژئولوژیکی درختان در زیستگاههای کم آب وتفکیک تعرق درخت به آب زیرزمینی ورطوبت مربوط به ناحیه غیر اشباع به منظور تلفیق این ایده در مدلهای عددی آبهای زیرزمینی است. این تحقیق به مسائل موجود و جهت تحقیق در آینده نیز پرداخته است.

Hydrogeologiczna rola drzew w środowiskach wodno-limitowanych

Abstrakt

Badania terenowe udowodniły, że przetrwanie wielu rodzajów drzew w środowiskach wodno-limitowanych (ŚWL) zależy od ich dostępności do wód gruntowych. Tego typu drzewa maj zdolnoś przetrwania okresów bezopadowych i susz dzięki bezpośredniemu poborowi wód podziemnych lub kapilarnych za pomoc systemu korzeni, które mog wnika w głb ziemi nawet do głębokości kilkudziesięciu metrów. Tego typu drzewa s również bardzo sprawne w znajdywaniu wody w strefach aeracji, co redukuje zasilanie wód podziemnych. Biorc pod uwagę, że środowiska wodno-limitowane charakteryzuj się niskim zasilaniem wód podziemnych i że drzewa mog zużywa znaczne ilości wód gruntowych, składnik ten nie powinien by pomijany w bilansach wód podziemnych, modelowaniu i zarzdzaniu wodami podziemnymi. W rzeczywistości pobór wód podziemnych przez drzewa w środowiskach wodno-limitowanych jest niedoceniany albo lekceważony ze względu na ograniczon wiedzę w tej dziedzinie. Niniejszy artykuł przedstawia obecny pogld na hydrogeologiczn rolę drzew w środowiskach wodno-limitowanych, metodykę rozdziału transpiracji drzew na komponent pochodzcy z wód podziemnych i komponent pochodzcy ze strefy aeracji oraz włczenie tych komponentów do modeli numerycznych wód podziemnych. Problemy zwizane z tego rodzaju badaniami zostały naświetlone, a także wskazano kierunki przyszłych badań.

A função hidrogeológica das árvores nos meios ambientais limitados em água

Resumo

Estudos baseados em trabalhos e medições de campo evidenciaram que, em meios ambientais limitados em água (MALA), várias espécies arbóreas dependem das águas subterrâneas. Especificamente, estas árvores sobrevivem à estação seca e às secas por extrair água directamente da zona aquífera ou da franja capilar através um sistema de raízes que pode atingir várias dezenas de metros em profundidade. Estas árvores são também muito eficientes em captar a humidade do solo na zona não saturada, diminuindo a recarga aquífera. Dado que os MALA são tipicamente caracterizados por uma recarga baixa e que as árvores podem extrair quantidades significativas de água subterrânea, este consumo não deveria ser desprezado nos balanços hidrogeológicos, na modelação e na gestão do recurso hídrico. Na prática, o consumo de água subterrânea pelas árvores em MALA é subestimado ou omitido devido à falta de compreensão deste processo. Este artigo revisa o estado actual de conhecimento sobre a função hidrogeológica das árvores nos MALA, a partição da transpiração arbórea nas contribuições da zona saturada e da zona não saturada e a integração desta partição nos modelos numéricos de fluxo. Realçam-se os problemas envolvidos nesta investigação e discutem‑se possíveis rumos de investigação futura.

Гидрогеологическая роль деревьев в условиях ограниченного во

Абстракт

Эксперименты уже доказали, что многие древесные породы в условиях ограниченного водоснабжения (УОВ) зависят от грунтовых вод. Типично, такие деревья выдерживают засушливые сезоны и периоды засухи потребелнием воды непосредственно из зоны грунтовых водов или из края капиллярной зоны своими кореневыми системами, которые могут углубляться до нескольких десятков метров. Такие деревья также очень эффективны в нахожденнии почвенной влаги в верховодной зоне, и таким образом они уменьшают восстановление запасов подземных вод. Учитывая, что УОВ типично охарактеризованы уже низким количеством подземных вод, и что деревья могут расходовать значительное количество грунтовых вод, такое «потребеление» грунтовых вод не должны быть упущено в баллансе, моделировании и управлении ресурсами грунтовых вод. Потребеление деревьями грунтовых водов на практике в УОВ или недооценено или пренебрежено из-за недостаточного знания об том явлении. В данном обзоре, обсуждаются современное состяние понимания гидрогеологической роли деревьев в регионах с ограничиненным водоснабжением, проблемы разделения транспирации деревьев, их вклад в восстановление уровня грунтовых вод и уровня вод фреатической зоны, и вопросы внедрения данного разделения в численные модели. Также обсуждаются проблемы, которые встретились в данном исследовании и предлагаются будущие направления для исследований в данной области.

Su miktarı kısıtlı ortamlarda agaçların hydrojeolojik rolü

Özet

Birçok ağaç (türünün) su kısıtlı (WLE) “water limited environment” ortamlarda yeraltı taban suyuna bağımlı olduğu çoktan arazi deneyleri ile ispatlanmıştır. Tipik olarak bu tür ağaçlar yağışın az olduğu mevsimlerde ve kuraklıkta direkt tabandan, onlarca metreye kadar inebilen köklerinden kapiler olarak aldıkları su ile ayakta kalabiliyorlar. Bu tür ağaçlar doymamış alanda toprak nemi bulmakta çok etkinler ve yeraltı suyunun yeniden dolumunu azaltıyorlar. WLE (su kısıtlı ortamların) tipik az dolum ile karakterize olduğunu ve ağaçların önemli ölçüde yeraltı suyu tüketebileceğini göz önünde tutarsak, bu tabansuyu “tüketimi” tabansuyu dengelenme, modelleme ve kaynak yönetiminde ihmal edilmemeli. Pratikte WLE lerde ağaçların yeraltı suyu çekisi bu konu hakkında ki bilgi eksikliği yüzünden ya hafife alınıyor yada önemsenmiyordu. Bu inceleme, su miktari kısıtlı ortamlarda ağaçların hydrojeolojideki rolünü, yeraltı suyunda ağaçların terleme paylaşımını ve doymamış alan katkılarını, ve bu paylaşımın sayısal yeraltı su modellerine entegrasyonunu tartışmaktadır.

Vai trò địa chất thuỷ vn của cây trong môi trường thiếu nước

Tóm tắt

Nhiều thí nghiệm cho thầy hầu hết các loài cây sống trong môi trường thiếu nước (MTTN) đều phải phụ thuộc vào nguồn nước ngầm. ặc biệt, ở nhóm cây chống chọi được qua nhiều mùa khô và hạn hán nhờ hút và sử dụng nuớc trực từ nguồn nước ngầm hoặc từ hệ thống các mao quản, chúng có thể có bộ rễ n sâu tới hàng chục mét. Nhóm cây này còn có khả nng hấp thụ ẩm độ đất tại vùng không bão hoà, do đó làm giảm lưu lượng nước bổ sung cho tầng nước ngầm. Mặt khác, do đặc trưng của MTTN là khả nng bổ sung nước thấp nên trong tính toán cân bằng, mô hình hoá cũng như quản lý tài nguyên nước ngầm, ta không thể bỏ qua lượng nước ngầm đáng kể được hấp thụ bởi nhóm cây này. Tuy nhiên trong tính toán, lượng nước ngầm hấp thu bởi cây nếu không bị ước tính thấp hơn thực tế thì cũng bị bỏ qua do sự hiểu biết còn hạn chế về hiện tượng này. Phần tổng quan dưới đây tổng hợp lại hiểu biết hiện tại của chúng ta về vai trò địa chất thuỷ vn của các loài cây trong MTTN, sự phân tách của quá trình bốc hơi nước ở cây vào trong tầng nước ngầm và vùng không bão hoà, cũng như quá trình tích hợp của quá trình phân chia đó trong các mô hình tính toán trữ lượng nước ngầm. Phần thảo luận sẽ tập trung vào các vấn đề gặp phải trong nghiên cứu đồng thời đề xuất các hướng nghiên cứu mới trong tương lai.

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© Springer-Verlag 2008

Authors and Affiliations

  1. 1.ITC-International Institute for Geoinformation Science and Earth Observation EnschedeThe Netherlands

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