Sanchez Jose Thesis 10-08

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WATER through the INTEGUMENT of BUILDINGS

: LEARNING from ADAPTATIONS of XEROPHILES

by

JOSE JOAQUIN SANCHEZ, M. ARCH

A THESIS

IN

ARCHITECTURE

MASTER OF SCIENCE


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Acknowledgments

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TABLE OF CONTENTS

Acknowledgments ........................................................................................................ i

ABSTRACT ................................................................................................................... iv

LIST OF FIGURES .......................................................................................................... v

Chapter 1 INTRODUCTION ........................................................................................... 1

1.1 Discussion of the Problem .................................................................................. 1

1.2 Objective ............................................................................................................. 2

2 BACKGROUND RESEARCH ..................................................................................... 3

2.1 Water Scarcity ..................................................................................................... 3

2.2 Defining Desert Environments ............................................................................ 6

2.2.1 Chihuahuan Desert ......................................................................................... 7

2.3 Strategies for Water Efficiency in the Built Environment ................................... 8

2.3.1 Rainwater Harvesting ...................................................................................... 8

2.3.2 Wastewater Reuse .......................................................................................... 8

2.4 Adaptation to Arid Environments ....................................................................... 8

2.4.1 Xerophytes ...................................................................................................... 9

2.4.2 Xerophilous Fauna ........................................................................................ 12

2.4.3 Conclusion ..................................................................................................... 18

3 DESIGN RESEARCH .............................................................................................. 19

BIBLIOGRAPHY .......................................................................................................... 20


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ABSTRACT

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LIST OF FIGURES

FIGURE 2.1.1 WATER STRESS INDICATOR (WSI) IN MAJOR BASINS ......................................................................4

FIGURE 2.1.2 GLOBALMAP OF ARID LANDS ................................................................................................................4

FIGURE 2.1.3 ESTIMATED POPULATION DENSITY IN 2015 ......................................................................................5

FIGURE 2.4.1 CYLINDROPUNTIA (OPUNTIA) BIGELOVII, JOSHUA TREE NATIONAL PARK, CA ......................... 11

FIGURE 2.4.2 COLOR TONES OF DESERT ANIMALS ................................................................................... ............... 14

FIGURE 2.4.3 SEM DORSAL SKIN OF M. HORRIDUS .................................................................................................. 15

FIGURE 2.4.4 PHRYNOSOMA CORNUTUM AND MOLOCH HORRIDUS, DORSAL VIEW ............................................ 16

FIGURE 2.4.5 DISTRIBUTION OF WATER DROPLET MILLISECONDS AFTER CONTACT TO INTEGUMENT OF

SEVERAL LIZARDS ............................................................................ ..................................................................... 17

FIGURE 2.4.6 HONEYCOMBMICRO-ORNAMENTATION ............................................................................................ 17


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Chapter 1 INTRODUCTION

1.1 Discussion of the Problem

The increasing global issue on water scarcity has placed a lot of pressure on

water conservation strategies. There are a few strategies already implemented within

the construction industry, yet not powerful or efficient enough to make a valuable

impact on the issue at hand. Naturally, a multitude of efficient strategies for water

conservation may already be observed through nature. Desert biota have evolved to

very harsh conditions in which temperatures are intense and the environment is arid.

Their adaptive strategies have allowed them to survive and flourish. Many of these

adaptations for survival may be observed through the integument of many desert flora

and fauna. Similarly in architecture, the facade is one of the most important

components of a building in protecting its' inhabitants from the environment and the

harsh conditions. The building envelope filters the exterior environment from the

interior where humans may live and interact comfortably.

A problem currently faced by architects is how to implement water conservation

strategies with their designs. Most of these systems are rudimentary by design and

functionality. They are implemented as "add-ons" to a building, a scheme in which the

catchment source, transportation or flow of the water, storage component, wastewater

reuse systems, and mechanical systems are completely separate entities.


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1.2 Objective


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2 BACKGROUND RESEARCH

2.1 Water Scarcity

The survival of all known living things depends on one substance, water.

Although Earth contains large sums of water, only a fraction is readily available for

consuming. We will first look at various statistics involving water to understand the

global issue. While water covers approximately 70% of the Earths surface, the United

Nations Environment Programme (UNEP) estimated freshwater to account for about

2.5% of global water. From the global freshwater, about 70%, over two-thirds, is locked

up in glaciers and permanent snow cover, in other words, not easily nor readily

accessible. Water that is accessible is found as groundwater, nearly 30% of freshwater,

and on the surface as rivers and lakes, which account for a measly 0.3% of freshwater.

Although groundwater does encompass less than one-third of freshwater, groundwater

sources are being depleted at a faster rate than they are able to replenish.

At this point I would like to point out the distinct correlation between the

locations of water stress in major basins and the locations of drylands, arid

environments, seen in Error! Reference source not found. and Figure 2.1.2. Drylands

are classified as zones where precipitation is offset by evapotranspiration, evaporation

from surfaces and transpiration by plants. The UNEP defines drylands as tropical and

temperate areas with an aridity index of less than 0.65. The drylands are further

classified into four sub-types: hyper-arid, arid, semi-arid, and dry sub-humid lands. It is

in these dryland environments that water overuse is damaging the environment globally

in major basins. The high overuse seems to occur in regions heavily dependent on
http://en.wikipedia.org/wiki/United_Nations_Environment_Programmehttp://en.wikipedia.org/wiki/United_Nations_Environment_Programme


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irrigated agriculture, areas undergoing rapid urbanization, and rapid industrial

development. UNEP estimates that 1.4 billion people are currently living in river basin

areas that are closed, meaning that water use is exceeding the minimum recharge

levels, or are near closure.

Figure 2.1.1 Water Stress Indicator (WSI) in Major Basins

Figure 2.1.2 Global Map of Arid Lands


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(Millenium Ecosystem Assessment, 2005)

Figure 2.1.3 Estimated Population Density in 2015

The dangers of global water shortages and safe access to potable water is

greatly affecting nearly two billion people around the world, that is nearly 30% of the

world's population. Due to population growth rates, development pressures, and

changing needs and values, equitable sharing of water resources has become a complex

issue. It is anticipated by the World Water Assessment Programme (WWAP) that most

population growth will occur in developing countries, with regions that are already

experiencing water stress and in areas with limited access to potable water and

adequate sanitation facilities. The growing competition between different countries

and sectors has been placing increasing strain on the quality and quantity of freshwater

supplies. The U.N. Population Division estimates that by 2025, the world's population

will surpass 8 billion, with the possibility of nearly two-thirds of them living under water

stressed condition and nearly one-quarter, 1.8 billion, living in severe water scarce

regions, according to the Food and Agriculture Organization (FOA).


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water scarcity shows the problems cities in deserts will be facing. Water will become

more scarce and the environment will become harsher. Different strategies and

solutions should be looked in to in order to adapt our built environment to withstand

and overcome these problems. There are various movements looking to improve our

built environment and allow it to work with natural systems. The USGBC has

implemented the LEED system and addresses the issues of water through its Water

Efficiency credits. Yet we can find more inspiration and strategies already implemented

and functioning in nature, a look into biomimicry.

2.2.1 Chihuahuan Desert

This desert covers 175,000 square miles 1, making it one of the top three largest

desert regions in North America and the Western Hemisphere. The Chihuahuan Desert

straddles the U.S.-Mexico border in the central and northern portions of the Mexican

Plateu, stretching from the southeastern corner of Arizona across southern New Mexico

and west Texas in the United States. It runs deep into central Mexico, including the

state of Chihuahua, northwest Coahuila, northeast Durango, and parts of Zacatecas and

San Luis Potosi. This desert is usually called a rain shadow desert because two massive

mountain ranges border this region, the Sierra Madre Occidental to the west and the

Sierra Madre Oriental to the east. These mountains block most of the moisture from

the Gulf of Mexico and the Pacific Ocean from reaching the land, and are the main

reason that this desert developed.

The Chihuahuan Desert is considered a high-elevation desert because a

greater portion of the desert lies above 4,000 ft. in elevation. Winters in the

1 Sources, such as the WorldWildLife and DesertUSA claim the Chihuahuan Desert reaches up to 196,700square miles, which would make it the largest desert in North America, second in the western hemisphere.


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Chihuahuan Desert are typically cool where nighttime temperatures drop below

freezing over 100 times a year on average. During summers, daytime high temperatures

average between 95 to 104 degrees Fahrenheit. Unlike the other deserts, the

Chihuahuan Desert does not have a winter rain season. Instead, over 90% of the annual

rainfall occurs between the summer months of July and October. This correlation of

summer seasonal rainfall and summer seasonal high temperatures greatly increases the

amount of moisture potentially lost through evaporation and evapo-transpiration,

compared to the amount of moisture gained through precipitation.

2.3 Strategies for Water Efficiency in the Built Environment

2.3.1 Rainwater Harvesting

Rainwater harvesting is nothing new in the construction industry. Archeological

evidence attests to the capture of rainwater in China dating back 6000 years. In Israel,

ruins of cisterns are still visible that were used to store runoff from hillsides for

agricultural and domestic purposes over 4000 years ago(Gould & Nissen-Petersen,

1999). In India,

2.3.2 Wastewater Reuse

2.4 Adaptation to Arid Environments

For survival in arid environments, two necessities are essential; moisture-

capture and moisture-conservation, and defense against both the physical and climatic

environments. Arid conditions create problems for all desert organisms, therefore


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water must not only be obtained by diverse means, but also effectively conserved. The

biota must have defensive mechanisms for predators as well as protect mechanisms for

the hard conditions(Lull, 1920). The biological processes of animal tissues can function

only within a relatively narrow temperature range. If this range is exceeded, through

high or low temperatures, the organism more than likely dies. This creates a delicate

life in the desert, yet both plants and animals have been able to flourish.

2.4.1 Xerophytes

(still have more information to organize in this section) Desert plants have

adapted several ways to obtain water and to store water. While some desert flora store

water in their leaves, roots, and stems (as other plants do), other desert plants have

long taproots that penetrate to the water table if present or have adapted to the

weather by having wide-spreading roots to absorb water from a greater area of the

ground. A succulent plant must be able to guard its water hoard in a desiccating

environment and use it as efficiently as possible. The stems and leaves of most species

have waxy cuticles that render them nearly waterproof when the stomata is closed.

Water is further conserved by reduced surface areas; most succulents have few leaves,

no leaves or leaves that are deciduous in dry

Moisture suspended in the air and which, while it may form dew, is not actually

precipitated in the form of rain, must be rendered available, and this may be brought

about by one of two ways, possibly by the deliquescence of the salty encrustation so

characteristic of desert plants or by the mechanical collection of dew by the hairs which

bedeck their surface. In either case, the water instead of evaporating back into the

atmosphere may be largely absorbed by the plant. The saline coat and the pubescence


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are therefore hygroscopic (having the property of readily imbibing moisture from the

atmosphere) in their effect. Whether or not the plant can utilize the moisture thus

collected is, however, open to question (Lull, 1920).

Most days, the aridity allows the sun to shine unfiltered, cloudless, through the

atmosphere continuously from sunrise to sunset. This intense solar radiation produces

very high summer temperatures which are lethal to non-adapted plants. At night much

of the accumulated heat radiates through the same clear atmosphere and the

temperature drops dramatically. Daily fluctuations of 40F (22C) are not uncommon

when humidity is very low. Microphylly (the trait of having small leaves) is primarily an

adaptation to avoid overheating and reduces water loss. A broader surface has a

deeper boundary layer of stagnant air at its surface, which impedes convective heat

exchange. A larger leaf requires transpiration through open stomates for evaporative

cooling. Since the hottest time of year is also the driest, water is not available for

transpiration. Desert plants that do have large leaves produce them only during the

cool or rainy season or else live in shaded microhabitats. There are a few mysterious

exceptions, such as Datura wrightii (Jimson Weed) and Asclepias erosa (Desert

Milkweed). Perhaps their large tuberous roots provide enough water for transpiration

even when the soil is dry.

Leaf or stem color, orientation, and self-shading are still more ways to adapt to

intense light and heat. Desert foliage comes in many shades (rarely in typical leaf-

green) such as gray-green, blue-green, gray, or even white. The light color is usually due

to a dense covering of trichomes (hairlike scales), but is sometimes from a waxy

secretion on the leaf or stem surface. Lighter colors reflect more light (heat) and thus


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remain cooler than dark green leaves. Other plants have leaves or stems with vertical

orientations; two common examples are jojoba and prickly pear cactus. This orientation

results in the photosynthetic surface facing the sun most directly in morning and late

afternoon. Photosynthesis is more efficient during these cooler times of day. Prickly

pear pads will burn in summer if their flat surfaces face upward.

Some cacti create their own shade with a dense armament/network of spines

that shade the stems, keeping them cooler than the surrounding air; Cylindropuntia

bigelovii (Teddy-bear Cholla), Figure 2.4.1, is one of the most striking examples. The

spines not only shade the Teddy-bear Cholla, they are also a very light color to reflect

the solar heat. Columnar growth forms maximize exposure to light early and late in the

day while avoiding excessive heat from the mid-day sun. Many Barrel Cactus lean to the

south so that a minimum of body surface is exposed to the drying effect of the midday

sun. Cactus pay a price for these water-saving adaptations -- slow growth. Growth may

be as little as 1/4 inch per year in the Barrel Cactus, and most young sprouts never reach

maturity.

Figure 2.4.1 Cylindropuntia (Opuntia) bigelovii, Joshua Tree National Park, CA

(World Botanical Associates, 2013)


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Other plants have developed rosettes of succulent leaves that collect dew and

fog. Yet another group of woody plants may drop their leaves during dry times and

often have long taproots as well. Many desert plants have adopted an ephemeral life

cycle, surviving as seeds, bulbs or dormant shrubs for long periods between

unpredictable rains.

2.4.2 Xerophilous Fauna

Most fauna native to desert environments have evolved both behavioral and

physiological mechanisms to solve the heat and water problems. Many xerophile

animals (more specifically mammals and reptiles) are crepuscular, that is, they are active

only at dusk and again at dawn; times when temperatures begin to lower or before they

get too high. Many others are completely nocturnal, restricting all their activities to the

cooler temperatures of the night. Bats, many snakes and rodents, and some larger

mammals like foxes and skunks, are nocturnal; and can be found sleeping in a cool den,

cave, or burrow by day. Similarly, smaller desert animals, including many mammals,

reptiles, insects, and amphibians, burrow below the surface of the soil or sand to escape

the high temperatures from the desert surface. Rodents have been observed to plug

the entrances to their burrows to keep out hot, desiccating air. Rhinos on the other

hand, relish wallowing in mud, which helps cool them especially during the hottest

months and helps protect them from parasites. Water storage, ectopic fat storage and

structural adaptations, shape and size, of desert organisms are important adaptations

for desert animals. Low values for resting metabolic rate at thermo-neutrality are


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reported for many desert mammals, and it is suggested that this helps these animal to

conserve both energy and water.

Desert animals have also have evolved various morphological characteristics, in

which all contribute, in one way or another, toward xerophilous adaptations. Equally

ingenious are the diverse mechanisms various animal species have developed to

acquire, conserve, recycle, and condense moisture to water.

Coloration is perhaps the most conspicuous of the adaptations, which not only

furnish protection against other animals, but is also used to minimize, or maximize,

absorption of solar heat. Colors observed on pelage and integument of these animals

are generally light and tinted-gray, tan, brown, or red, harmonizing with the color of the

surrounding sand or rock (Lull, 1920). To avoid overheating, desert cottontails have

behavioral higher activity periods at night, have light-colored fur, and most interestingly,

large ears with blood vessels just below the skin level that can radiate body heat to the

air.


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Figure 2.4.2 Color Tones of Desert Animals

(counterclockwise from topleft): Armadillo, Desert Tortoise, Diamondback Rattlesnake, Kangaroo Rat, Jack

Rabbit (Desert USA, 2012)

Several desert lizard species, classified as horned lizards, have developed special

morphological characteristics to collect water with their bodies' surfaces and

"transport" the captured water to the mouth for ingestion. Nature's way of rain- or

moisture-harvesting. The water can originate from air humidity, fog, dew, rain or even

from humid soil. There are a few lizards observed to have such rain-harvesting

capabilities, of which two stand above the rest: the Moloch horridus (Thorny Devil) and

the Phrynosoma cornutum (Texas Horned Lizard).

In 1923, H.W. Davey and Buxton first recorded observations of the integument

of a Moloch horridus, Thorny Devil, readily absorbing water from a puddle and drawing

the absorbed water towards its' head. This absorption demonstrated hygroscopic

properties of the integument enabling what was called "trans-cutaneous" absorption of


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water from dew or water puddles. In 1962, Bentley and Blumer contradicted the first

theories of absorption through trans-cutaneous action and demonstrated that the M.

horridus actually drinks the water by passively transporting it through capillary action of

the skin to the mouth. In 1982, Gans, Merlin, and Blumer, reexamined the M. horridus

skin with the aid of Scanning Electron Micro-scope (SEM) photographs, Figure 2.4.3, and

attributed the water-flow to capillary forces generated by channels between the lizard's

scales. In 1987, Schwenk and Greene described a similar system in Phrynocephalus

helioscopus (sunwatcher toadhead agama), yet reported a stereotyped posture

exhibited by the species whenever it was sprayed with water. The posture involved

lowering of the head, raising the splayed hindquarters, and protruding the tongue to

initiate capillary action.

Figure 2.4.3 SEM dorsal skin of M. horridus

The lizard Phrynosoma cornutum demonstrated similar behavior, yet including a

stereotyped posture of flattening the body and spreading of the dorsal surface to

maximize interception of raindrops. Comparable behavior has not been observed in the

M. horridus (Sherbrooke, 1990). Presence of integument capillary microstructures,


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similarly as reported with the M. horridus, was confirmed on the P. cornutum, but

capillary flow seems to be less effective for this lizard (Sherbrooke, 1990). For the P.

cornutum, capillary transport of water was reported to be more significant during light

precipitation, as the water amount collected by the integument is not large enough to

flow towards the mouth by gravity alone.

Figure 2.4.4 Phrynosoma cornutum and Moloch horridus, dorsal view

(Rowe, Maisano, Humphries, Hodges, & Pianka, 2013)

In a more detailed report in 1993, Philip Withers described the volume of water

held in the interscalar capillary system to be about 3.7% of the M. horridus' body mass.

He concluded that one ecological role of the hydrophilic skin of the thorny devil is the

direct absorption of rain that falls onto the skin, uptake from puddles, and enables

water absorption from moist sand through the capillary system. In 2011, a team from

Germany tested the application of a water droplet onto the integument of three

species, M. horridus, P. cornutum, and Phrynocephalus arabicus. The application led in

all three species to an almost immediate spreading of the water as shown in Figure


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2.4.5. They concluded that the honeycomb-like micro-structure on the three lizards

created a 'superhydrophilic' surface (Comanns, et al., 2011).

Figure 2.4.5 Distribution of water droplet milliseconds after contact to integument of several lizards

Figure 2.4.6 Honeycomb Micro-ornamentation


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(A) M. horridus shows the honeycomb-like micro-ornamentation all around (B) P. cornutum shows clear

honeycomb micro structures, but mainly at periphery of the scales. (C) Phrynocephalus arabicus

honeycomb structures appear like dimples. (D) (E) and (F) shows the micro ornamentations marked for

better orientation

2.4.3 Conclusion

The intention of studying the behavioral, physiological, and morphological

adaptations of desert biota is to understand how they efficiently collect rainwater and

conserve what water they ingest. Certain morphological adaptations of cacti allow

maximum retention of water and decreased evapotranspiration. The various reports on

these animals demonstrate how certain systems, interscalar capillary channels and

integument patterns, work together to transport water for ingestion. Once imbibed,

the physiological and behavioral adaptations allow for maximum conservation of water

through the dry seasons.

A building's integument may similarly work as a system to maximize rainwater

harvesting, minimize evapotranspiration, and retain water for consumption or reuse.

This may be achieved through a couple or several materials working together, each with

their set properties to achieve a similar goal; conserve water. A building's skin will not

only protect us from the harsh environment, but will also work as nature does to

provide its inhabitants with water.


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3 DESIGN RESEARCH


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BIBLIOGRAPHY

Buxton, P. A. (1923). Animal Life in Deserts : A Study of the Fauna in Relation to the Environment.

London: Edward Arnold & Co.

Comanns, P., Effertz, C., Hischen, F., Staudt, K., Bohme, W., & Baumgartner, W. (2011, April). Moisture

Harvesting and Water Transport Through Specialized Micro-Structures on the Integument of

Lizards. Beilstein Journal of Nanotechnology , 204-214.

Crawford, C. S. (1981). Biology of Desert Invertebrates. New York: Springer-Verlag Berlin Heidelberg.

Davey, H. W. (1923). The Moloch Lizard, Moloch horridus. Victorian Naturalist , 58-60.

Desert USA. (2012, November). Retrieved from DesertUSA: http://www.desertusa.com

Food and Agriculture Organization. (2013, April 3). FOA Water . Retrieved from FOA.org:

http://www.fao.org/nr/water/

Gould, J., & Nissen-Petersen, E. (1999). Rainwater Catchment Systems for Domestic Supply: Design,

Construction and Implementation. London: Intermediate Technology Publications.

Gutterman, Y. (2002). Survival Strategies of Annual Desert Plants. New York: Springer-Verlag Belin

Heidelberg.

Louw, G., & Seely, M. (1982). Ecology of Desert Organisms. New York: Longman Group Limited.

Lull, R. S. (1920). Organic Evolution. New York: The MacMillan Company.

Lusk, P., & Simon, A. (2009). Building to Endure: Design Lessons of Arid Lands. Albuquerque: University

of New Mexico Press.


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Millenium Ecosystem Assessment. (2005). Millenium Assessment Reports . Retrieved from

http://www.millenniumassessment.org/en/index.aspx

Mishra, A. (2001). The Radiant Raindrops of Rajasthan. New Delhi: Research Foundation for Science,

Technology, and Ecology.

Peterson, C. C. (1998, September). Rain-Harvesting Behavior by a Free-Ranging Desert Horned Lizard

(Phrynosoma platyrhinos). The Southwestern Naturalist, 43 (3), 391-394.

Rowe, T., Maisano, J., Humphries, J., Hodges, W., & Pianka, E. (2013, Septempber). Retrieved from

Digital Morphology: http://www.digimorph.org/

Sherbrooke, W. C. (1990, September). Rain-Harvesting in the Lizard, Phrynosoma cornutum: Behavior

and Integumental Morphology. Journal of Herpetology, 24 (3), 302-308.

Texas Water Development Board. (2005). The Texas Manual on Rainwater Harvesting. Austin.

UN Water. (2013, March). Statistics . Retrieved March 2013, from UNWater.org:

http://www.unwater.org/

UNEP. (2013, June). Vital Water Graphics . Retrieved from UNEP.org:

http://www.unep.org/dewa/vitalwater/rubrique17.html

Vesely, M., & Modry, D. (2002). Rain-Harvesting Behavior in Agamid Lizards (Trapelus). Journal of

Herpetology, 36 (2), 311-314.

Ward, D. (2009). The Biology of Deserts. New York: Oxford University Press Inc.

Whitford, W. G. (2002). Ecology of Desert Systems. San Diego: Elsevier Science Ltd.

Wiscombe, T. (2009). Structural Ecologies. Beijing: AADCU Publication.


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Withers, P. (1993, September). Cutaneous Water Acquisition by the Thorny Devil (Moloch horridusL

Agamidae). Journal of Herpetology, 27 , 265-270. Retrieved from

http://www.jstor.org/stable/1565146

World Botanical Associates. (2013, October 7). Opuntia Cactaceae . Retrieved from World Botanical:

http://www.worldbotanical.com/opuntia.htm

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