From Guest Blogger and Huge 2GreenEnergy Supporter Gary Tulie:  California Drought – Adapt or Die?

(I hope readers will enjoy this very thoughtful article on the drought we’re experiencing here California; it was written by my friend and colleague Gary Tulie, of Buckinghamshire England. – ed)

 

How serious is the California drought? That is the multi-billion dollar question.

Already, the governor of California has brought in the state’s first mandatory water restrictions, requiring a 25% reduction in water consumption by residents. Farmers who are not directly covered by the restrictions are required to develop drought management plans including measures for cutting back.

The trouble is that ground water extraction was already running at twice the level of replacement by rain and snow, even before the drought intensified so that the water table is rapidly dropping resulting among other things in an increase in tectonic stresses and the level of earthquake risk.

http://www.bbc.co.uk/news/science-environment-27393811

The drought is thought to be the worst in 1200 years, and some scientists now think that the current drought and heat wave conditions are well on the way to becoming the new norm with future conditions only getting worse. Drier conditions reduce humidity levels which in turn allow temperatures to rise, speeding the melting of snow and reducing precipitation. This combined with accelerating climate change is likely to feed a self sustaining cycle in which hotter drier conditions dominate.

http://www.waterinfo.org/press-clipping/February-16%2C-2015–

One NASA scientist has warned that California has only around one year’s worth of reservoir water left and a greatly diminished level of ground water, and that little or no contingency has been considered for the drought to persist over, for example, a 20-year period.

http://www.theguardian.com/us-news/2015/mar/16/california-water-drought-nasa-warning

In short, if substantial adaptation measures are not adopted very soon, it appears that the “organic fertiliser” will hit the rotating air circulator.

What can be done?

Clearly, a 25% reduction in urban water consumption is not going to solve a problem of this magnitude in a state where agriculture uses 80% of extracted water, and is not directly required to meet the same 25% reduction target as members of the public. A much more radical program of reduction is essential with an initial suggested target of 50% reduction in net water use in ALL sectors, and no guarantee that further savings beyond that will not be required to achieve sustainable water use.

http://www.slate.com/articles/technology/future_tense/2014/05/_10_percent_of_california_s_water_goes_to_almond_farming.html

To achieve 50% reduction in agricultural water use will require a major shift in crop selection, with a mix of drought-tolerant varieties of conventional crops, and new crops entirely using plants which are inherently much better at tolerating extreme heat and drought.  Ideally, this will be combined with smart drip irrigation regulated by an array of soil moisture sensors, Allowing for differential irrigation across a field, watering the driest areas most whilst giving less water to areas where the soil is already damp.

Solutions may include switching to dry climate crops

Nuts

Pistachios thrive in semi-arid and near-desert conditions. These are far more sustainable for California in terms of water use than almonds which are currently grown in large quantities.

Fruit

There are a number of cacti which produce edible fruit such as Prickly pear, Yellow Pitaya, and Red Pitaya (Dragon fruit),

http://www.hort.purdue.edu/newcrop/ncnu02/v5-378.html

Also baobab, date palm, fig and cherry tomatoes are good in a hot dry climate.

Vegetables

Cassava, squash, shallots and cucumbers like hot dry conditions.

Seawater Greenhouse

A relatively simple technological solution exists in which crops are grown in greenhouses, the sides of which are made up of large area cardboard / cellulose evaporators, over which sea water is trickled resulting in a large amount of evaporation fuelled by hot air and either natural breezes, or fans. Water is then condensed on surfaces cooled by incoming sea water and captured for irrigation.

Such greenhouses can reportedly generate 100,000 litres of water per hectare per day (around 12,500 gallons per acre) in hot conditions, of which around 20,000 litres are used to irrigate the greenhouse crops. (Irrigation requirements are greatly reduced by evaporative cooling of the greenhouse, and by the high relative humidity achieved by the process.)

Additional crops can be planted outside the greenhouse, possibly under shade netting, taking advantage of the cooled humidified air flowing out of the greenhouse.

Such facilities can be used among other things for intensive cultivation of salad crops.

http://seawatergreenhouse.com/process.html

Irrigation with Treated Sewage

Water recovered from treated sewage can easily be made safe for irrigation, and California can no longer afford to throw away this valuable resource.

Water Catchment Planning

On some occasions when rain finally does fall, large quantities run off hard surfaces, causing flash flooding, severe damage, and loss of most of the water to sea.

A number of strategies can be used to counter this.

Carefully planned upland afforestation and land management can allow storm waters to remain on the high ground for long enough for them to soak into the soil, replenishing the aquifers. This also offers a measure of protection to downstream areas from flash flooding.

We also need to consider sand dams, i.e., small dams on seasonal streams backfilled with sand. Water soaks into the sand and is held behind the dam where it is protected from evaporation. Such dams can sometimes, in effect, store considerably more water than their volume, as the flow of water from the hills is slowed sufficiently that additional water is stored in the subsoil and/or makes its way into aquifers.

http://www.excellentdevelopment.com/what-we-do/pioneering-sand-dams

We need also to consider porous hard surfaces, e.g., in England where in certain locations prone to flooding, parking areas are required by planning law to be porous to allow water to soak into the soil.  Such surfaces will have much the same advantages as sand dams as compared to hard waterproof surfaces such as concrete or bitumen.

Interception dams on storm water drains – such dams can fill up every time there is a significant rain event, provide an additional measure of flood prevention, and can be pumped out to water treatment and storage facilities for later use. London is currently building a huge storm sewer to prevent raw sewage from flooding into the Thames following heavy rains.

Gray Water Recycling / Roof Water Collection

Urban water requirements can be substantially reduced by using roof-collected rainwater and also partially treated water from sinks and washing machines for non-potable applications such as flushing toilets and irrigating garden plants.