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.
By
Nelson Peñaherrera Castillo
PIURA CITY, Peru - One of the most extended prejudges 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 sucesion of cliffs, 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. From the two first, one is binational, the Chira Basin, or Catamayo-Chira Basin most properly, that is shared with ecuador's Loja Province. 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.
This has lead the officials to propose a management plan working in two completely different scenarios, the excess and the absence 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.
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.
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 vulnerability 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.
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 particularly 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.
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 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 diverting 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 second or 396200 gallons per second,
and hold 35 million cubic meters or 9,2 billion gallons. A top source said
FACTORTIERRA 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 regarding proposals:
- The first one could begin amid both lakes through the building of a 22-kilometer or 14-mile canal which could lead near where the sechura Drain ends, at san Pedro Beach (Vice District).
- The second one could start in the middle of La Niña and connect to the Virrilá estuary, probably an ancient lead of Piura River or the intermitent Cascajal River, through a 11-to-16-kilometer or 7-to-10-mile canal.
- The third one could departure from the south of La Niña to Olmos Depression, at Reventazón Beach, through a 26-kilometer or 16-mile canal.
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 cannot 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."
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 proper would be to say it is going to build a diverting canal and a reservoir."
The second controversy is technical-type. It is supposed the idea of Coscomba Project is building a diverting 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, it would 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 excessive flow, and eliminating 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 aritmetical 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.
Other actions in this
component are: to delimit the marginal strip of rivers and creeks, annual
di-sedimentation (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.
Additionally, an early alert
system would be designed, although there is no clear details yet, considering
the geographical particularities and the existent connectivity 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?
© 2018 Asociación Civil Factor
Tierra. All Rights Reserved. Photos featured on this entry by Nature and Culture International,
distributed by El Regional de
Piura, Eduardo Nizama/La Unión District Municipality/file, iguel Chávez, distributed by FACTORTIERRA, Jhony Dioses for FACTORTIERRA, and graphics provided by CRHCCHP/GoRePiura.
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