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Anti-Disaster Re-Engineering
Almost all Piura region will have to be intervened for preventing problems caused by the abundance of water - or its lack.

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By Nelson Peñaherrera Castillo
FACTORTIERRA.NET


One of the events increasing the vulneribility where the water of Piura Region generates, were fires like this, affecting the Andean slopes in Ayabaca and Huancabamba (photo) provinces during the second half of 2016.
Photo by Nature and Culture International, distributed by El Regional de Piura / file.


PIURA CITY, Peru - One of the most extended prejudgges by the people visiting Piura is believing that the whole territory is flat when the reality points out that the Andean Range, from its first spurs, occupies its half. And the fact is relevant when we want to explain natural events  like the floods during  a El Niño time.

The territory does not go down progressively to the sea but the coast is a sucession of clifs, creeks, and even depressions under its level. Add to this two valleys  with completely different identities despite to be separated by few miles.

That is the reason why the officials have understood that the natural disasters management  is foreseable when there is a good basins integral management, and we have three in Piura: two belonging to the Pacific Broad Basin and one to the Amazon Broad Basin. Fron the two first, one is binational, the Chira Basin, or Catamayo-Chira Basin most approppriately, that is shared with ecuador's Loja Probince. The second one is entirely Piura's - Piura, actually.

From those two ones, the Piura Basin could be the  most vulnerable of the region due to its geographical particularities: it begins  above 3000 meters or 9800 feet altitude, and trying to lead into the sea, it first finds a depression superior to -30 meters or -100 feet. And like we explain it before, to understand the critical point it means, we have to remember that the water flows attracted by the terrestrial gravity force.


The strategy for reducing risks linked to natural disasters in Piura Region is working preventively in the causality zone (the right part of the territory on the map, the east), so the impact area (the left side of the territory on the map, the west) does not suffer from the abundance of water, or its scarce.
Graphic provided by CRHCCHP/GoRe Piura.

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This has lead the officials to  propose a management plan working in two  completely different scenarios, the excess and the abscence of water.

"Such proposal has been declared regional interest by the Agreement 1443-2017  of the Regional Council, and made as own by the Regional Government, turning it into the leading prospective conceptual framework  for the reconstruction of Piura Region," the Regional Government of Piura (GoRe Piura, as in Spanish) and the Regional Council For Hydric Resources Of Chira-Piura Basin (CRHCCHP, as in Spanish) sustain on a work paper.

Water Technology: Chira-Piura Water Management System.

The another aspect is the Piura Basin has been artificially connected to Chira's  since 1948 when the Peruvian Government transferred Quiroz River water to Chipillico River to start up the San Lorenzo Valley, which began to establish since 1968. As a consequence, what happens along the Quiroz course, that leads naturally into the Chira, and even what happens at the Chipillico, that also leads into the Chira, impacts in the Piura River due to the web of canals, drains, and even natural spillways used by the San Lorenzo Dam.

The San francisco Creek is one of the main connectors between both basins  just beginning the medium course of Piura River, but down the water there is another contact point, the Daniel Escobar Canal, built in the 1970s decade, for transferring  directly the Chira River's stored water in the Poechos Dam, ended and put in service during 1976. Unlike the Piura, the Chira has a constant flow of water and it can reach colossal loads when El Niño rains to be presented.

In short and according to the CRHCCHP, it is about a 29852,86-square-kilometer or   11526,25 square-mile land (similar to Armenia, in Asia). The Piura Region's total surface is 35892 square kilometers or 13857,98 square miles (quite bigger than the state of Maryland), so the work area equals 87,48% of its political demarcation. In fact, it covers 56 of the 65 districts located in the eight provinces of the territory, where 1725488 people live.

Also, The Chira is now the main sweet water source for the whole coast of the region, especially the Piura Metro Area, where approximately 0,65 million people live, according to 2017 Census.


The main problem in Piura Basin lowlands is the Piura River does not lead directly into the sea, but it first fill depressions at the Sechura Desert. As many towns are just a couple of feet above the sea level, a heavy rain is enough to boost a flash flood, like this in La Unión, about 20 miles to the south of Piura City, on January 31st, 2017.
Photo by Eduardo Nizama/La Unión District Municipality/file.


Control The Cause, Control The Consequence
According to GoRe Piura and CRHCCHP, to save the lowlands of Piura it has to work  preventively at the highlands, what implies to intervene "... fundamentally at the zone  of the causality by regulating the load of the river for reducing the vulneribility at the impact zone, mainly facing the danger of floods and water scarce in the Chira-Piura Basin."

In the specific case of the Chira Basin, according to the proposal, it would be necessary to intervene the summits  and slopes in Lagunas, Sapillica, and Frías Districts, all in Ayabaca Province. The main problem is the deforestation, that accelerates the soil erosion and causes its slide.

Lagunas District (with Pacaipampa and Ayabaca) concentrates the nascents of torrents and creeks feeding the Quiroz River. In Sapillica, it happens something similar with Chipillico River. Remember both feed the San Lorenzo Valley, what, technically, is part of the Piura Basin.

The nascents located in Frías District does feed directly to the Piura River, mainly through Sáncor and Yapatera Rivers,those lead up the water of San Lorenzo Valley, and specifically to the south of Malingas Sector. When those two peaceful flows load extraordinarily during the rainy periods, break the road between the cities of Tambogrande and Chulucanas, the same like San francisco and Carneros Creeks, in the middle of San Lorenzo.

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But, as it was said previously, the authorities consider that the major priority is along Piura River's course from its many nascents located  in Huarmaca, Canchaque, and Lalaquiz Districts, Huancabamba Province, and particularily in Chalaco District, Morropón Province. Meanwhile in Salitral District, Morropón, they consider it must join  Huarmaca District, Huancabamba, due to they share a forest what, also, is a private area of conservation.

At this point, the trick consists in guaranteeing the water supply toward the plains, avoiding its flowing to be violent and destructive. The proposed task is the conservation of the so-called green understructure: protecting the natural forests and páramos, keeping the soils, and implementing the Regional Fund of Water.


One solution to prevent the overloads of Piura River could flood aggresively in Piura lowlands is building reservoirs to download the volume. One of the biggest is projected to be in La Matanza District, one of the rainiest zones across the region. This is Laynas Sector, in that district, receiving a heavy rain on March 24th, 2017.
Photo by Miguel Chávez, distributed by FACTORTIERRA.NET/file.

The polders
At the plains, the proposal is building little reservoirs with enough storage capability allowing to download the Piura River huge loads, so they do not overcome 1700-to-2000-cubic-meter-per-second or 449k-to528K-gallon-per-second loads. Remember the flood of Piura, on March 27th, 2017, was caused by a load over than 3400 cubic meter per second or 898180  gallons per second.


The plan of Piura Region authorities is building a network of reservoirs along Piura River to download its violent overflows. Even building spillways for the lakes at the depressions of the Sechura Desert.
Graphic provided by CRHCCHP/GoRePiura.

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The reservoirs would be located at Buenos Aires (La Maravilla Sector) and La Matanza Districts, Morropón, and the Coscomba Area, 26 de Octubre District, Piura Province. Their function would be to download the big volumes of water and to hold them.

In all cases, the river would be connected to the reservoirs through divertion canals. In La Matanza case, it would be downloaded until 2500 cubic meters per second or 660000 gallons per second, and hold 296 million cubic meters or 780 billion gallons; in Coscomba, it would be downloaded 1500 cubic meters per secon or 396200 gallons per second, and hold 35 million cubic meters or 9,2 billion gallons.

A top source said FACTORTIERRA.NET  there are no plans yet  to allow seeing  where they will be located specifically, how they will look like.

And as the Sechura Desert turns into a natural reservoir when its lakes overflow and join, mainly Ramón Grande and La Niña, the project includes  to build a spillway to the sea, and there are three regardin proposals:

In all cases, it is about to reduce the existent water level to 4,5 meters or 15 feet altitude for carrying it to the sea level. The gravity will do the rest of the work.

"The matter is Zapallal Formation, calcareus, called caliche [A surface deposit containing sodium nitrate and other minerals], so the Piura River can not erode it, and reaching this point, it begins to dam, flooding Piura City and Lower Piura Valley," the CRHCCHP sustains; "this flow will provide continuity and eases the La Niña Lake way-out to the sea."


The peaceful San francisco Creek can become a huge and violent river when it rains heavy between January and April. This actual photo, taken amid Malingas and Palominos Sectors, Tambogrande District, shows how much it can grow potentially.
Photo by Jhony Dioses for FACTORTIERRA.NET.


Benefit Or Risk?
However, in Coscomba Project case, there are two controversies.

The most anecdotal one is about the polder name assigned by the authorities, but not correct as one specialist thinks. A polder is a land extension gained to the sea through the building of a dam to hold the water, which is furtherly pumped out for having big dry extensions of terrain. The technique has been mostly used in Netherlands and Belgium since 14th century, and it has allowed to have more lands for the urban and agrarian development.

"I understand there was a German consultant who brought the term," a specialist said us, "but the approppriate would be to say it is going to build a divertion canal and a reservoir."

The second controversy is technical-type. It is supposed  the idea of Coscomba Project is building a divertion canal from up the water of Los Ejidos Dam, North Piura Metro Area, bringing it along its western side to a low point where the Coscomba Lagoon was once upon a time. For Architect Julio Gianella, this is a bad idea because it could make all this area prone to an eventual flood. So, itwould create another risk area additional to the own course of the river's.

He believes that, adding to reforestation at Andean summits, it would have to make many low-capability reservoirs along Piura Basin, which go downloading the eexcessive flow, and elliminating it for having the next load. He affirms the idea is endorsed by other local scholars.

But the first specialist debunked that to us based on an aritmetic criterion: the proposed derivation canal can hold until 1300 cubic meters per second or 343400 gallons per second, and the Piura River flow passing through  the regional capital city can support until 2500 cubic meters per second or 660400 gallons per second. Then, a 3800-cubic-meter-per-second or 1,38-million-gallon-per-second load could not represent any risk. Also, the water flow would be controlled from Los Ejidos.

The question is what would happen if the Piura River receives loads over 3800 cubic meters per second, as happened in 1998.


The projected Coscomba Reservoir, in 26 de Octubre District, West Piura Metro Area, would try to save the cities of Piura and Castilla when the Piura River threatens to overflood.
Graphic provided by CRHCCHP/GoRePiura.


Other actions in this component are: to delimit the marginal strip of rivers and creeks, annual dissedimentation (that includes the drains also), and to build and to keep river defenses, plus to correct the course of the rivers and to reinforce the bridges connecting the cities of Piura and Castilla.

The last part of the proposal includes to implement new macro-drainage systems in the cities of Castilla and Piura by optimizing the existent drains and adding underground reservoirs beneath parks and avenues, which would lead in the Piura River.


Another critical point of the Piura River is when it runs beside Tambogrande City and grows until colossal flows. This is the point when it turns going down from the Andean range to the Sechura Desert.
Photo Courtesy by Jimmy Farfán.

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Additionally, an early alert system would be designed, although there is no clear details yet, considering the geographical particularities and the existent connectiveness levels among institutions and the people, so it would be necessary to empower their skills, what is also considered in the plan.

executing it integrally could take about eight years, or the equivalent of two regional government administrations, CRHCCHP's representative Ronald Ruíz Chapilliquén estimated during a self-summoned meeting of Piura's citizen platforms, in Curilcas, Pacaipampa District, last August 4th. The whole could cost about US$ 764,8 million.

"The adequate information is not enough, it's necessary the citizen support of every territory for the proposal to be gotten," he had said.

It is announced the first months of 2019 could be lightly rainer than usual, not reaching the 2017 extremes. The prevention plan proposed by the authorities is ambitious. How much of that will be ready, at least, to receive one alone heavy rain?

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