(BY HUGO)

A discussion on cloud seeding in a recent post motivates the reporting of this news (in French - article in L'Essor by Sibiri Konaté) to illustrate the type of operations currently performed in Africa.

Mali is paying a total of around US $27 000 000 for cloud seeding to a consortium led by Weather Modification Incorporated, an American company. The rain enhancement programme was initiated in 2005. The increase in rainfall is reported to vary between 15% and 50% depending on the region. Analysis performed on provoked rainwater reportedly shows no alteration in water quality.

Interestingly, Saskatchewan, British Columbia and Alberta are on the list of Weather Modification Incorporated's clients. The operations in Alberta are still going on and relate to hail suppression.

UPDATE: Another article from David Dembele in Journal du Mali (in French) provides additional details on the seeding campain.

(BY HUGO)

The Utah Water Law and Water Rights Blog informs that the Utah Legislature passed a bill permitting the capture and storage of precipitations.

This seems to be part of a trend in water law towards regulating ever closer to the upstream reaches of the hydrologic cycle. Such a trend appears justified in areas traditionally left unregulated in order to avoid a "tragedy of the commons" given the increasing exploitation of and competition for a limited resource.

Salient points of the Utah legal provision are:

- Reliance on the doctrine of beneficial use tied to the parcel on which the water is captured and stored;

- Constraints on the volumes of rainwater that can be stored - 2 500 gallons if stored in an underground container, and 2 x 100 gallons covered containers if stored above ground. Question: if stored above ground in uncovered container, would there be no volume limit? If such is the case, would this be an indirect invitation to alter extensively overland run-offs by changing the morphology of one's parcel?

(BY HUGO)

In a previous blog, there was a mention of how it might be more prudent to establish what are the limits to up-scaling rainwater harvesting.

The issue is essentially that harvesting superimposes an artificial catchement connected to cisterns on top of a real catchment where environmental uses require a minimum of water to remain healthy.

A paper by Stephen Ngigi, «What is the limit of up-scaling rainwater harvesting in a river basin?», examine this question... and concludes that there is a clear need for additional research to understand the effects of rain harvesting up-scaling. Nonetheless, Ngigi states that:

«Increased withdrawals of water in rainfed and irrigated agriculture may have negative implications on water availability to sustain hydro-ecological ecosystem services. The expected shifts in water flows in the water balance would affect both nature and economic sectors depending on direct water withdrawals (Rockstrom et al., 2001). Upgrading rainfed agriculture through RWH that enables dry spells mitigation, would involve the addition of water, through storage of runoff, to the rainfed system. The cumulative effect of RWH may have an impact on downstream water availability within a river basin scale. The effects are bound to be site specific and need to be studied further (Rockstrom et al., 2001).»

In a more recent article, «Identifying Barriers to Widespread Implementation of Rainwater Harvesting for Urban Household Use in Ontario», Chantelle Lidi et al. identify barriers faced in implementing rainwater harvesting. The most significant barriers are as follows:

«Initial capital cost, liability for potential health risks, limitations on the end use of rainwater, the Building Code’s poor differentiation between rainwater, greywater and non-potable water, and a lack of public environmental commitment. Health risks would be a paramount concern for public health officials, but were only a moderate concern for the majority of building practitioners interviewed.»

Rainwater harvesting is certainly a solution to some water management problems and a priori a sustainable practice.

However, a familiar worrying pattern seems to appear: constraints to up-scaling are identified, but limits to development remain unknown.

Would precaution and prevention demand that limits be identified before going forward with rainwater harvesting on a large scale?

(BY HUGO)

Timothy Wheeler from the Baltimore Sun reports that a compromise has been reached at the legislative level to go forward with storm-water pollution rules which are supposed to take effect on 4 May 2010.

The law and its rules require developers to better control rainfall washing off their projects so that there is no more runoff and it is no more polluted than it was before construction began. Builders also have to reduce the amount of pavement so more rain could soak into the soil naturally, instead of collecting it in large ponds or underground tanks.

(BY HUGO)

As mentioned in previous posts, rainwater management is an emerging trend.

Rainwater can be abstractly conceived as the ultimate upstream point in the hydrologic cycle which regenerates and replenishes freshwater resources for anthropogenic uses.

Pollution and reduction in quantities of unallocated water result in increasing water stress. To avoid shortages, users are moving from dowstream closer to upstream in the hydrologic cycle: historically, people have moved from «excess» surface water flowing in rivers to the sea, to groundwater sources directly dependent on rainwater infiltration, and now onward to rainwater directly harvested when and where it falls...

Other abstract upstream sources in the hydrological cycle such as desalination or cloud seeding are either more costly or technologically immature. As a result, rainwater harvesting will probably become an important aspect of water resources management in the near future.

The multiplication of news related to rainwater harvesting already suggests that this is already the case. The fact that water stressed regions currently develop projects for harvesting rainwater confirms that including rainwater within management regimes is essential.

The Los Angeles Times reports that a proposed law applicable to new home buildings and development projects would oblige rain capture and reuse to avoid runoff and waste. The generation of runoff would be sanctioned by a mitigation fee of $13 / gallon.

Coca-Cola and its partners in India have completed 16 rainwater harvesting projects in Madhya Pradesh for a total harvesting capacity of 3,600 cubic meters / year.

And in Queensland, Australia, rainwater harvesting from roofs combined with wastewater reuse and recycling at an onsite treatment plan will reduce the cost of a new development by AU$6 millions.

(BY HUGO)

As discussed in a recent post, rainwater harvesting is indeed gathering momentum in Western USA.

The Legal Planet Blog has a post on this water supply augmentation method.

Basically, urban rainwater harvesting transforms water proof city areas (paved roads, roofed perimeters,...) into small artificial watersheds superimposed on natural watersheds. Rainwater that runs off in the artificial watershed ends up in a cistern and gets disconnected from the environment.

Rainwater harvesting is certinaly a good idea and an improvement on wasting water through unitary sewers. However, water is a limited resource: there is only a limited volume of it in one place at one point in time. The implementation of large scale rainwater harvesting should be coupled with residual environmental flow protection (as in Australia) to avoid further water deprivation for environmental uses.

Given the American penchant for big absolute solutions, it would seem adequate to remain extra cautious about implementing rainwater harvesting on a huge scale before the safeguards are there to protect environmental water uses. Is there legal environmental flow protection in California?

(BY HUGO)

One quote from an article about extreme drought in the LA Times attracts the attention on a water resources management method that is underused (exept in India?) but fast gaining ground and attracting increased inerest:

«Griggs cited rainwater harvesting and demand management as the least expansive options for increasing water supplies. Pipelines and dams were among the most expansive options he said.

"Urban storm water is a large untapped source of water generated close to where it is needed. ...In most Australian cities, as much water falls on that city as the city needs", Griggs said.

In Queensland, Australia's fastest-growing state, with 2.7 million residents, about 20% of the population has installed rain-catchement tanks since 2006, when the area received just 7.4% of its average annual inflow to the major dam that supplies it. In 2007, that flow had declined to just 4%.»

In these 3 paragraphs, it's possible to find all the reasons that will make rainwater harvesting a very important component of all water management regimes in the near future: 1) supply side oriented (allowing overall water use increase to some degree); 2) cheapest; 3) locally managed.

In the last few years, rainwater harvesting has already attracted interest in US Western states and Texas. Some German cities are metering residential storm runnoffs to encourage rain harvesting and domestic use (toilet flushes, laundry...). New Building regulations may force rainwater harvesting in large building project in the South of England...

In short, rainwater harvesting will become a big issue in water law and management, especially since it may result in conflicts with prior downstram users and environmental uses.