Rainwater Harvesting for Drylands and Beyond Vol 1 Notes - desertGo.info

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Rainwater Harvesting for Drylands and Beyond Vol 1 Notes

<UL> Introduction Chapter 01 Chapter 02 Chapter 03 Appendix 1 Appendix 2 Appendix 3 Appendix 4 </UL>

1 Introduction

captures precipitation and uses it as close as possible to where it falls

Small-scale strategies are the most effective and the least expensive, so they are emphasized here. They're also the safest and easiest to accomplish.

Live within the Sonoran Desert where annual rainfall averages just 12 inches (305mm)

planted shade trees that grew tall around the house, lowering summer temperatures enough for us to eliminate our evaporative cooler (improved insulation, painting the house's exterior white, and passive ventilation also helped)

daily municipal water use dropped from the Tucson residential average of 114 gallons (43 2liters) per person per day to less than 20 gallons (7 5liters)

On our1/8-acre(0.05-ha )lot and surrounding right-of-way we currently harvest annually over 100,000 gallons (378,500 liters) of rainwater within a 1,200-gallon (4,540-liter) tank, the soil, and vegetation

[rain is the primary source of water, it fills secondary sources like rivers, lakes, and aquifers]

In 1930 there were 170 irrigation wells tapping the Ogallala aquifer that stretches 1,300 kilometers from the Texas panhandle to South Dakota; by 1959 there were over 42,000. ^14

As Charles Bowden writes, "By the sixties the High Plains had 5,500,000 acres under irrigation and men were working through the night to direct the flow from the ceaseless pumps." 15

Blue Gold Report, globalwater consumption is doubling every 20 years - more than twice the rate of human population growth. If current trends persist, by 2025 the demand for freshwater will be 56% more than is currently available. ^16

The Ogallala aquifer is being depleted eight times faster than nature can replenish it. ^17

We drain our communities by diverting our rainwater away from rather than infiltrating it into our landscapes

impervious asphalt, concrete, and buildings

Fig I.4A/B showing street runoff versus catch [pdf 26] <P>Fig I.5A/B [pdf 28]

[current] system reminiscent of a hospitalized patient on an intravenous drip <P>Development in Atlanta, Georgia and surrounding counties contributes to a yearly loss of rainwater infiltration ranging from 57 to 133 billion gallons. If managed on site, this rainwater -which could support annual household needs of 1.5 to 3.6 million people - would filter through the soil to recharge aquifers, and increase underground flows to replenish rivers, streams, and lakes.^18,19

Twenty-five percent of the land within incorporated Tucson is covered with impervious cover such as asphalt, concrete, or buildings. 20 In higher density cities such as Los Angeles, California, over 60 % of the land surface is covered with pavement. 21

construct bowl-like landscapes (concave shapes) to passively harvest

harvest storm water runoff from streets

Hydrate rather than dehydrate communities. Across India traditional rainwater strategies are being revived to enhance local water resources. In the Alwar District people from 650 villages built or rejuvenated around 3,000 smalle arthen check dams conserving rainwater and increasing infiltration by 20%. Community-led forestry projects worked to reclaim cut and eroding lands. Sixteen years after the project's beginning, groundwater levels have risen almost 20 feet (6 meters); forest cover increased by 33%; and five rivers that previously dried up each year now flow perennially. Increased agricultural production has exceeded the cost of the original investment by 4 to 1. ^23

We see water flowing from taps

In Arizona, ground water pumping has dried up or degraded 90% of once-perennial streams, rivers, and riparian habitats.^24

In California's Central Valley, overuse of ground water has collapsed the aquifer soil structure, causing a permanent loss of natural water storage capacity amounting to more than 40% of the combined storage capacity of all human-made dams and surface reservoirs in the state.^25

In 1972, water diversion from China's once mighty Yellow River prevented it from reaching the sea for the first time in history. That year the flow did not reach the ocean on 15 days. In 1997, it failed to reach the season 226 days. ^26

The average American household could reduce water demands by 33 to 50% each year. ^27

Additional water-conserving technologies and methods could cut agricultural water demands by close to 50%, and industrial water demands by 50 to 90% without sacrificing economic output or quality of life. ^28

Every kilowatt-hour (kWh) of coal-generated electricity uses about 1 pound of coal, produces 2 pounds of C02 ,and uses just under 0.5 gallons of water. ^30,31

Plant within your water budget

[Washing machines, 30-50 (114-189 liters) gal/load, 10 gal /load Energystar, saving 7k (26,500 liters) gal/year per USA household] ^33,34,35

evaporative cooler in Phoenix, Arizona, consumes an average 65gallons (246 liters) per day.^37

[misting coolers] 2,160 gallons(8,175 liters) per month to cool 1,000 square feet (92.9m2) of patio [by only 7F/3.8C]

Low-water-use native shade trees use less water than misting systems while cooling temperatures up to 20°F (11.1°C). ^39,40

In Tucson a 400-square-foot (37.1-m2) pool will lose 16,000 gallons (60,60 0 liters) of water per year to evaporation

Toilets account for up to 30% of all indoor potable water use in a typical U.S.residence.^48

Only 2% of America's rivers and streams remain free-flowing and undeveloped. ^53

The U.S. Global Water Corporation has signed an agreement with Sitka, Alaska, to export 18 billion gallons per year of glacier water to China where it will be bottled in one of that country's "free trade" zones to exploit cheap labor. The company brochure tempts investors "to harvest the accelerating opportunity... as traditional sources of water around the world become progressively depleted and degraded." ^55

Water scarcity attracts market forces; water abundance does not.

Fig I.8B Water Cycling [pdf 33]

[Tuscon] In the past 100 years, over pumping has lowered this ground water table by more than 200 feet (61 m) in some areas, and it continues to drop an additional 3 to 4 feet (0.9-1. 2 m) more each year. ^61,62

Once-perennial reaches of the Santa Cruz River and numerous springs have dried up.^63

Cottonwood, willow, and mesquite "bosques" or forests that used to line our waterways have died. ^65

Pollutants from local landfills ,businesses, and industry have migrated down to our aquifer, creating several Environmental Protection Agency (EPA) Superfund sites. ^66

4 billion dollars to construct, and 60 to 80 million dollars a year to operate, the Central Arizona Project (CAP), which diverts water from the Colorado River and pumps it 1,000 feet (305 m) uphill in an evaporation-prone canal over 300 miles (483 km) through the desert to reach our city. ^67

FigI.10A/B Before and after [pdf 35]

Projected population growth and increased water use is predicted to outstrip Tucson's "renewable" water supplies by 2025. ^68

The Colorado River -designated America's Most Endangered River due to mounting problems with radioactive, human, and toxic waste in the water ^69 - has been over-allocated to the point that the southern most reaches of the river are severely diminished, crippling much of the Colorado River Delta's ecosystem and economy.^70

If the states upstream from Arizona on the Colorado River, and if Mexico below, take the full shares of Colorado River water granted them there will not been enough water left to meet Arizona's needs and fill the CAP canal in drought years. ^71

[1/4 acre in Tuscon recieves 67kgal (253.6k liters), avg 3 person house uses 120k gal (454.2 liters), all outdoor needs could be met with rain] ^73

[cycle water, multiple uses]

[by conserving] We enhance our own water resources and those of others, especially those down stream and downslope.

.Rain is our primary water source (fig.I.12); .Grey water is our secondary source; .Municipal water or groundwater from private wells is strictly a supplemental source used only in times of need.

Approximately 235 gallons per person (capita) per day (gpcd) (890 liters pcd) of rainwater compared to a 1998 total use of approximately 165 gpcd (625 Ipcd) delivered by municipal water companies form municipal and industrial uses.^74

Doesn't harvesting rain water deplete the water resources of those downstream?

[create forested hillside, slow the water not stop it, could reduce surface flows, will increase spring and underground flows, recharge aquifers,]

Passive water-harvesting earthworks (see volume 2) are typically 50 times cheaper than cisterns and can hold far more water.

[rainwater harvesting laws, check your location]

[building code says don't infiltrate water 10 ft (20 ft with basement) or closer to foundation of house]

www.HarvestingRainwater.com

Chapter 1

The Man Who Farms Water and the Rainwater-Harvesting Guidelines

ZvishavaneWaterResourcesProject.

"You start catchment upstream and heal the young, before the old deep gullies downstream," says Mr. Phiri.

[all work done with] Hand tools and the sweat of Mr. Phiri and his family.

"The soil, "Mr. Phiri explains, "is like a tin. The tin should hold all water. ..."

Fig1.2 Mr. Phiri's farm [pdf 43]

berm 'n basins (dug out basins and earthen or vegetated berms laid out on contour), [swales]

Mr. Phiri turned things around by digging a series of large "fruition pits" (basins about 12 feet long by 3 to 6 feet wide by 4 to 6 feet deep) in the bottoms of all the drainage swales on his land. [gov swales off contour to drain, made drought worse but erosion better]

He influenced CARE International in his region to the point that it shifted much of its work from giving away imported food, to helping people implement Mr. Phiri's methods of planting the rain and growing their own food.

[helped a local school harvesst water, some teachers left and wrecked more land before returning to see his success.]

Mr. Phiri turned to me with a huge smile and said, "Remember, children are our flowers; give them rain and they will grow and bloom."

To observe your site, sit in the dust and dance in the rain, through all the seasons.

It costs nothing to observe, think, and plan.

Sub-watersheds

[starting at the top lets you work with the smallest amounts of runoff possible]

[small is cheaper, can be done by hand, can teach, mistakes are small, lots of small often better than one big]

Central Soil and Water Conservation Research and Training Institute in Dehra Dun, India, found that increasing the size of a dam's catchment from 2.47acres (1ha) to about 4.94 acres (2ha) reduces water yield per hectare by as much as 20 percent. ^3

"In a drought-prone area where water is scarce, 10 tiny dams with a catchment of 1 ha each will collect much more water than one larger dam with a catchment of 10 ha." ^4 [less displacement, better for environment, probably cheaper, probably save water to evap in transport]

Michael Evenari's book Making Water Everybody's Business states," While a 1 hectare watershed in the Negev yielded as much as 95 cubic meters of water per hectare per year, a 345 ha watershed yielded only 24 cubic meters of water/ha/year. In other words, as much as 75% of the water that could be collected (in the larger watershed) was lost (to evaporation and the soil)."^5

Evenari "...during drought years with less than 2 inches (50mm) of rainfall, watersheds larger than 123.5 acres (50ha) will not produce any appreciable water yield, while small natural watersheds will yield 4,400-8,800 gallons (20-40 cubic meters) per hectare, and micro catchments smaller than 0.24 of an acre (0. 1 hectare) [will yield] as much as 1.7,597-21,997gallons (80-100 cubic meters) per hectare."^6

Fig 1.16A/B source/sink, straight/zig-zag [pdf 53]

Always Plan for an Overflow Route, and Manage That Overflow Water as Resource ^7

hardy sisal plants (Agave spp.) that use little water, require almost no maintenance, produce large amounts of biomass to hold back water ands oil, and produced fiber [will stay green longer and if animals eat they can die from the fibers]

Chapter 2

Ben Haggard's great little book, Drylands Watershed Restoration

Rivers and streams generally flow throughout the year; in spite of the fact that rain is a localized and fairly infrequent event in arid settings. Even in rainy climates, rain occurs a relatively small percentage of the time. Rivers have a sustained flow because most of the water is actually stored in the soil where it slowly releases into the drainage. In disturbed watersheds, this slow and sustained release is disrupted. Water runs rapidly off the ground's surface rather than soaking into the ground. This process creates floods followed by drought. To repair such a watershed, infiltration of the water in to the ground must be increased. -Ben Haggard

Living systems create complex interactions with water. Water falls as rain. Trees intercept this water, directing it in to the ground where a layer of organic material deposited by the trees absorbs and holds it. Some of the water flows slowly through the ground where it supports the growth of forests and the sustained flow of rivers. Rivers act as transportation networks, allowing nutrients from the forests to wash down stream and fish and other animals to swim upstream, importing phosphate and other minerals into the forests. Water in the landscape also attracts and supports wildlife, the active planters, fertilizers, and maintainers of the forest. The forests breathe water back in to the air, where it condenses around particles also released by the forests. The clouds form and the entire process repeats it self."^2 {Dryland Watershed Restoration-byBenHaggard

(USGS) mapping.usgs.gov [topography maps]

"Surf Your Watershed" can be found at cfpub1.epa.gov/surf/locate/map2.cfm

CATCHMENT AREA (ft2) X AVG RAINFALL (ft) (X 7.48 gal/ft3) = TOTAL RAINWATER (ft3)

[calculate your "water budget"]

[water coefficient - the average that runs off a specific surface] .A roof or impervious paving (such as an asphalt street) : 0.80-0.9 5 .Sonoran Desert up lands(healthy indigenous landscape) : range 0.20-0.70, average 0.30-0.5 0 .Bare earth : range 0.20-0.75, average 0.35-0.5 5 .Grass/lawn : range 0.05-0.35, average 0.10-0.2 5 .For gravel use the coefficient of the ground below the gravel.

5 to 20% of runoff from impervious catchment surfaces such as roof can be lost due to evaporation,

[grey water]

tinaja-a desert water hole carved into bedrock

cistern, "You get more conservative as you see the water level fall," says Matt

10-gallon RV pump pressurizes the water

Chapter 3

clean roof materials such as metal, slate, tile, or elastomeric paints

Fig.3.1. Landscape [pdf 76]

Fig.3.6. Different terracing strategies for different grades of slope [pdf 78]

Infiltration basin

Fig.3.12. Roof runoff and bathroom sink grey water directed [pdf 81]

Imprinting

Fig.3.15. Vertical mulch variation (mulch-filled hole or trench) encouraging infiltration and retention of water deeper into the root zone of the soil [pdf 83]

An Introduction to Erosion Control by Bill Zeedyk and Jan-Willem Jansens.

[weld ends on culver pipe and turn on side for cistern] picture [pdf 91]

Check dams, gabions

"If you have scouring in an arroyo and no vegetation, you know the situation is out of control. If vegetation is established on the bottom you know the situation is more stabilized."

[west central NM] most success with asparagus, garlic, Egyptian walking onions, and Jerusalem artichokes [in check damed arroyos]

Ten pounds per square inch (psi) of water pressure is needed for the irrigation lines to function

Each foot a water source (tank) is raised above its destination (garden), gravity provides 0.43 psi of pressure.

Net and pan system

Chapter 4

[sun's position and movement throughout the year][wind, shade, etc][zone/sector plan]

A year-long study in Davis, California, monitored temperatures in two identical apartment buildings with different orientations to the sun. No heating or cooling systems were operated during this year. The study found that apartment units in the building with an east-west orientation (long walls facing south and north) and with small roof overhangs were 17°F (9.4°C) warmer in winter and 24°F (13.3°C) cooler in summer than apartments in a similar building with a north-south orientation (long walls facing east and west).^2 (See figure 4.5.) [pdf 101]

Box 4.2. Approximate Sun Angles by Latitude for Northern Hemisphere [pdf 102] www.srrb.noaa.gov/highlights/sunrise/azel.html www.srrb.noaa.gov/highlights/sunrise/sunrise.html www.esrl.noaa.gov/gmd/grad/solcalc/ www.geomancy.org/astronomy/sunfinder/calculator/index.html

[trees/vegetation shade the soil during the day keeping it cooler and hold in heat at night keeping it warmer.]

Cold-sensitive plants go on the warm winter-sun side of a tree or building. Hardy drought- and heat-tolerant plants go on the west side where afternoon sun is hottest and evapotranspiration is greatest. Cold-tolerant plants go on the cool winter-shade side.

Place sunken garden beds on the south or southeast side of pruned-up native mesquite trees to allow winter sun to hit the garden directly.

I can produce salad greens, artichokes, herbs, snow peas,garlic and onions, potatoes, carrots, Jerusalem artichokes, and edible flowers in full winter sun with mild temperatures and low evaporation rates. In the extreme heat of summer when evaporationrates increase, the diffuse shade of the mesquite keeps chiles, tomatoes, basil, eggplant, squash, gourds, and summer greens from prematurely wilting from exposure.

[solar arc, placement of trees (deciduous and evergreen) to arc/hug your house and provide maximum shading or heating by blocking or allowing summer and winter light.]

[concrete and asphalt collect heat and warm the surrounding area, as much as 10F in a Davis CA study. They also have 100% runoff][flagstone (or like) can be placed on the ground to create a patio area that is still permeable]

Appendix 1 - Patterns of Water Flow and Erosion

erosion can be seed as speed:volume:distance

[lots of problem-responses to erosion, lots of illustrations]

Look for sediment deposition, break-lines and keylines, high watermarks, scour holes, vegetation, and animals.

Southwest, water-needy broad-leafed cottonwood (Populu sfremontii) and sycamore trees (.Platanus wrightii) typically indicate the presence of springs, perennial water flow, or shallow groundwater levels

(Ambrosia deltoidea) are found in arid, drained zones

Short-term indicators of soil moisture include native annuals such as pepper grass (Lepidiu mthurberi) and abundant invasive annuals such as tumbleweed (Salsolaiberica).

Dragonflies are found near open bodies of water. A high number of toads probably mean that a water source is ephemeral or too small to support predatory fish.

Appendix 2 - Water Harvesting Traditions in the Desert Southwest - 1994 Permaculture Drylands Journal , Permaculture Drylands Institute

at Mesa Verde and Hovenweep National Parks, at numerous small dams in the upper Rio Grande and Chama drainages, and throughout the Pajarito Plateau

waffle garden, Zuni, [sunken bed with ground level berm or raised berm] grid gardens similar but with stone boarders,

gravel mulch, can keep soil/air warmer,

Anasazi, Hohokam, and Mogollon people - Sinagua culture around A.D .1000

That there was irrigation before the arrival of the Spanish is clear. Its exact extent and character is not. What we do know is that it was not as universal a trait of Pueblo agriculture in the past as it is now, and was only one of a wide range of farming techniques used.

At Santa Clara, river bottom cultivation was one small part of Pueblo agriculture. Typically, fields were scattered across the landscape at different elevations and in different environments to prevent a disaster

Hohokam of southern Arizona built substantial irrigation canals to divert water from large rivers, but the eventual failure of these projects contributed to the destruction of their "advanced" civilization

Anasazi area, dry farming seems to have been the rule, and irrigation was small in scale compared to the Hohokam

Anasazi, Originally simple swidden agriculture, Land was cleared, burned, and planted. As it was exhausted, new land was cleared. Eventually the original plot recovered and could be replanted. This extensive clearing increased erosion. Check dams and linear borders were being constructed late in the occupations of Chaco, the Mimbresarea, the San Juan Basin, and other sites, such as Pot Creek Pueblo near Taos. These structures were apparently an attempt to halt the serious erosion caused by deforestation and clearing, over use of wild plants, and foot traffic. Despite these conservation attempts, these areas were ultimately abandoned. When a prolonged drought struck in A.D. 1276-1299, the food production systems were already under stress from the high population densities. The combination of the drought with the environmental degradation caused by heavy farming and residential use probably led to final abandonment of settlements.

Refugees from these areas built grid gardens, techniques intended to prevent the start of erosion

[As populations increased, more land was needed, Anasazi became nomadic. After depleting all land around settlement they would move. Every 60-100 years. Could eventually return to old land that recovered. After learning 3 sisters they moved slower, more sedentary village lives.]

[Forced migrations in the 1300s, Anasazi learned to keep it small and let the land rest.]

Like the Chacoans and Hohokam, we believe that our technical "advances," power, and grandeur make us exceptions to the constraints of our environment. And just like them, our failure will come to us as a surprise.

Joel Glanzberg Regenesis Group (www.regenesis-group.com).

Appendix 3 - equations,

rules of thumb: you can catch 600 gallons per inch of rain on a 1k ft2 area, 27k gallons per inch of rain on an acre 1k liters per 10 mm rain over 100 m2 100k liters per 10 mm rain over hectare

different runoff from different surfaces, bare land, vegetated, hardpan, etc. Use appropriate runoff coefficient.

Sonoran uplands coefficient = 0.2-0.7 (avg 0.3-0.5) Bare earth = 0.2-0.75 (avg 0.35-0.55) Grassland = 0.05-0.35 (avg 0.10-0.25)

Net annual runoff catchment area(ft2) X rainfall(ft) X 7.48gal/ft X runoff coefficient = net runoff (gal)

each person consumes an average of about 50 gallons per day

gravity fed pressure = 0.43psi/ft height, the longer the hose the more friction,

storage capacity of a cylinder pi x (cylinder radius(ft))2 x effective cylinder height*(ft) x 7.48 gal/ft3 = capacity(gal)

cost per gallon stored: price of cistern(dollars) storage capacity(gal) = price of storage capacity (dollars/gal)

weight of water: stored water(gal) x 8.32 lb/gal = weight of stored water(lb)

Appendix 4 - Sample Plant Lists, Water requirement calcs, Tuscon AZ,

Box A4.1. Approximate Annual Water Requirements for Mulched Vegetable Gardens in Tucson, Arizona, Planted in Sunken Basins

50ft2 3,180gallons 100ft2 6,360gal. 150ft2 9,540gal. 200ft2 12,720gal. 250ft2 15,900gal. 300ft2 19,080gal.

4.5m2 12,080liters 9m2 24,160liters 13.5m2 36,250liters 18m2 48,080liters 22.5m2 60,420liters 27m2 72,500liters

Box A 4.2. Native Multi-Use Trees for the Tucson, Arizona Area [pdf 156]

Box A 4.3. Native Multi-Use Shrubs,Cacti, and Ground cover for the Tucson, Arizona Area [pdf 157]

Box A 4.4. Exotic Multi-Use Fruit Trees, Vines, and Cacti for the Tucson, Arizona Area [pdf 158]

Arizona Department of Water Resources for their Drought Tolerant/Low Water Use Plant Lists www.water.az.gov/adwr/Content/Conservation/LowWaterPlantLists/default.htm