|
|
- Hildebrandt, A., M. Al-Aufi, M. Amerjeed, M. Shammas, and E. A. B. Eltahir, 2006. Ecohydrology of A Seasonal Cloud Forest in Dhofar: I Field Experiment, submitted to Water Resources Research.
- Hildebrandt, A. and E. A. B. Eltahir, 2006. Ecohydrology of a Seasonal Cloud Forest in Dhofar: II Role of Clouds, Soil Type, and Rooting Depth in Tree-Grass Competition, submitted to Water Resources Research.
- *Milutinovic, M., K. Murtaugh, and E. A. B. Eltahir, 2006. A Proposal for Water Pricing in Kuwait, submitted to Water Resources Research.
* A paper co-authored by one or more of my students
Abstracts
Ecohydrology of A Seasonal Cloud Forest in Dhofar: I Field Experiment
Anke Hildebrandt, Mohammed Al-Aufi, Mansoor Amerjeed, Mohammed Shammas,
and Elfatih A. B. EltahirAbstract: Here, we describe the ecohydrology of a semiarid broadleaf deciduous forest in Dhofar (Oman). The forests are confined to a coastal area (and surrounded by desert), where the summer wet season is characterized by a persistent dense-cloud immersion. Using field observations we show, how clouds render the ecosystem particularly water conserving and therefore create a niche for a moist (woodland) biome in a semiarid area: First, horizontal precipitation (collection of cloud droplets on tree canopies) added valuable water in this semiarid environment, such that 2-3 times as much water was received below the canopy (net precipitation) compared to above the canopy (rainfall). Second, high stemflow (about 30% to net precipitation) led to concentrated water input around the stems. Third, transpiration was suppressed during the cloudy summer season, which allowed for storage of the received water. It was only used after the end of the wet season and lasted for the following three months, which roughly doubled the length of the growing season. Our results demonstrate that cloud immersion may shape ecosystem hydrology in significant ways, particularly in semiarid environments.
Ecohydrology of a Seasonal Cloud Forest in Dhofar: II Role of Clouds, Soil Type, and Rooting Depth in Tree-Grass Competition
Anke Hildebrandt and Elfatih A. B. EltahirAbstract: Using a dynamic vegetation model we investigate the role of summer cloud immersion on performance of trees and grasses. The predicted vegetation type depends on the assumed cloud cover during the wet season, with forest predicted for 100% cloudiness and grassland for clear sky. Clouds decrease available energy for evapotranspiration during the moist season, thus increasing deep infiltration and making more water available for tree transpiration after the end of the monsoon. Deeper rooting depths are associated with higher tree LAIs, and also increase competitiveness of trees through resource portioning. An efficient rooting depth exists, at which transpiration is maximized and all other fluxes in the water balance are minimized. The efficient rooting depth is deeper for coarse soils than for finer ones and deeper for dense cloud cover as compared to light cloud cover. Cloud cover creates a favorable seasonality in this ecosystem that is crucial for maintaining tree vegetation.
A Proposal for Water Pricing in Kuwait
Milan Milutinovic, Katharine Murtaugh and Elfatih A. B. EltahirAbstract: Kuwait is an arid country with limited natural water resources. Yet water consumption per capita is around 450L/capita/day, which is much higher than in many other countries in the world. Certainly one of the reasons for the high level of consumption is the fact that even though water has a pricing schedule in Kuwait, water bills are not collected efficiently. Consequently, there is some amount of water that is being wasted. The main objective of this paper is to study the potential impact of pricing as a tool for managing water demand in Kuwait. Due to a lack of empirical data regarding household consumption characteristics and price influences on demand, a demand model for Kuwait could not be constructed directly. Instead, water demand models described in the literature were adapted to Kuwait. A pricing schedule is proposed that consists of a free allowance followed by a constant water price. This proposal has the following logic: if water is consumed reasonably, it should be free. However, to limit over-consumption, water used beyond the amount of the allowance should be priced. Our results indicate that this pricing schedule would be efficient in reducing demand significantly. The model results suggest that a price of $1/m3 for water use in excess of a 150L/capita/day allowance would reduce the demand by about one third, with a range between 20 and 40 percent depending on the model used.