POLICY BRIEFJUNE 2015

INTRODUCTIONMindanao’s rich agricultural economy has been attributed, to a large extent, to its natural blessings as a typhoon-free region. Endowed with rich watershed resources irrigating its thousands of hectares of land, its economy has also supported flourishing industrial activities.

In the recent years, however, Mindanao has been absorbing the brunt of ferocious calamities, including a succession of the strongest typhoons to hit the country so far. The continuous denudation of the forest has resulted to, or aggravated the disasters that destroyed properties in magnitude not seen before, immobilizing industries, and claimed thousands of lives in one sweep.

The magnitude of destruction seemed to become the new norm in Mindanao. To get to the bottom of this destructive shift in the environmental panorama of Mindanao, the Mindanao Development Authority (MinDA) in partnership with the Mindanao Rivers Rehabilitation Task Force (MRRTF) has launched a rapid assessment under the Mindanao Nurturing Our Waters Program (MindaNOW).

This was conducted by researchers from Central Mindanao University (CMU). This study was formulated to come up with the current status and degree of impairment of each river system.

The result would guide and influence the formulation of interventions and

MINDANAO CRITICAL RIVERS RAPID ASSESSMENT

ISSN 2467-5571 (Online) Issue No. 2015 - 0002

TABLE 1. LIST OF ASSESSED CRITICAL RIVERS IN MINDANAO

Upstream sites of the watershed were not covered in the study due to inaccessible roads. In lieu of it, the midstream sections were assessed. Other than actual data-gathering, the concept of whole watershed assessment was also considered which included several contributory factors such as degree of slope, elevation, land cover and coverage of cultivation, stream orders, number of populations, geologic hazards and soil type of watersheds.

RATIONALEThis study (1) characterizes qualitatively and quantitatively the socio-economic, geomorphologic, vegetative and physio-chemical conditions of selected critical rivers in Mindanao, (2) produces GIS-generated maps regarding the socio-economic, geomorphologic, vegetative and physio-chemical conditions of selected critical rivers in Mindanao and (3) evaluates the degree of impairment and possible intervention for the selected critical rivers in Mindanao.

The critical rivers were selected through a set of criteria agreed by the by members of the Mindanao Rivers Rehabilitation Task Force (MRRTF) composed of several government agencies that include the DENR, DILG, MGB, NIA, DPWH, EMB, NEDA, DA and provincial governments of selected areas.

The rivers were not covered by master plans crafted for the major river basins in Mindanao. Process of selecting these rivers includes 1) setting up parameters, namely the role of river to development (agricultural, industrial, tourism/recreation, domestic use), susceptibility to flooding, and potential threat of flooding to socio-economic development (population, agriculture, and infrastructures); 2) indicative ranking of rivers according to the parameters; 3) refining the indicators and revalidation of ranking descriptions (DENR, EMB and RBCO), and 4) finalizing list of critical rivers for intervention.

Table 1 shows the list of all the 22 critical rivers covered by the rapid assessment characterization.

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MOST DEGRADED: KINGKING RIVER

The methods used include the combined technologies of Remote Sensing (RS), Global Positioning System (GPS) and Geographic Information System (GIS), along with field survey using interview questionnaire, generated rapid assessment instrument, and multi-parameter probe (HORIBA U-52G) for the determination of the water quality among the selected sampling sites. Secondary data were obtained from LGUs, NSO, EMB and other concerned agencies with the assistance of MinDA as regard socio-economic, demographic, land use/land cover, geomorphologic and other relevant information.

Established assessment sites were analysed through ocular surveys, giving emphasis on abiotic and biotic components. Midstream areas were assessed instead of upstream areas due to accessibility concerns. Other secondary data were also integrated in the analysis: degree of slope, elevation, land cover and coverage of cultivation, stream orders, population, geologic hazards, and soil type of the watersheds.

Rivers identified as critical were based on degree of degradation of their landscape, physical condition and surrounding biotic health. Corresponding significance of the river and its role in development was also considered in determining if river condition was critical.

Degree of importance was based on agricultural, industrial, tourism/recreation and domestic use. Susceptibility to flooding, based on floodwater depth, was another important factor considered in identifying a critical river.

Most importantly, a river’s potential threat of flooding to socio-economic development was also deliberated. Specifically, marked threats to population, agriculture (crops, livestock, and fisheries), infrastructure (roads, irrigation, and bridges) and social infrastructures (school and hospitals) were determined.

METHODOLOGY

Gravel exploited and stoked at the side of the river of Kingking (Upstream)

FINDINGS

A total of 22 identified critical rivers throughout Mindanao were assessed. Seven (7) rivers are from Region 9, two (2) from Region 10, three (3) from Region 11, nine (9) from Region 13 and one (1) from the Autonomous Region of Muslim Mindanao.

Watersheds of the assessed rivers in Region 9, Zamboanga Peninsula are elongated in shape, easier to manage due to slow disposal of water allowing the watersheds to absorb more water. This helps form small streams. However, the existing land cover and soil type of watershed also influence movement of water. Large cultivated areas and less forested areas may increase discharge runoff.

Watersheds also have high water holding capacity, but when the ground would be saturated with water due to continuous rainfall, mud slides may likely occur especially in steep slopes. Moreover, drainage pattern of all watersheds are disturbed as indicated by the low average bifurcation

Excessive sediments deposition at the downstream part of Kingking River

LEAST DEGRADED: SALUG RIVER

Visual bank failure in Salug River Visual turbidity of Salug River

values. These disturbances may refer to several activities such as quarrying and mining operations, and agricultural cultivation occurring in the areas. Most common observed modifications among Zamboanga rivers are the poor bank stability and severe river scouring affecting agricultural lands and even threatening the safety of nearby residents.

The observed moderate to extreme channelization of rivers is caused by bank erosions which widened the rivers. Heavily deposited sediments from erosion resulted into shallower rivers as well. All rivers failed the water quality standards of DENR Administrative Order 34 due to high turbidity and TSS concentrations in water implicated to have adverse impacts to environment and even to human health.

Richness of vegetative protection and streamside cover at the vicinity of Layawan, Dipolog and Miputak rivers/creeks are marginal and considered disturbed. This can be explained by the growing commercial and urbanizing areas traversed by the rivers. Other rivers, Dicayo, Sindangan and Salug, located in the rural areas, have relatively better vegetative status rated sub-optimal, a less suitable and less disturbed condition.

However, Sibuguey river was rated marginal in terms of the surrounding vegetation condition. Large cultivated areas cover riparian areas instead of natural vegetation that would serve as buffer against occurring floods.

For Region 10, all assessed rivers are also elongated in shape, and thus tread the same dangers as those studied in Zamboanga, with similar disturbances by existing quarrying and mining activities, land cultivation and presence of dam and other hydrologic structure.

Though abiotic assessments are with varying degree of degradation, both are however observed to be deteriorated. Severe eroded banks, extreme channel alteration and the thinning vegetation are mainly attributed to the history and

MOST DEGRADED: KINGKING RIVER

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LEAST DEGRADED: SALUG RIVER

the current excessive resource extraction such as small-scale to large-scale quarrying and gold mining, modifying the overall condition of both rivers.

Moreover based on the geomorphologic values, watersheds of Region 11 are all elongated in shape and its existing large coverage of less forested areas and cultivation in the watershed may increase discharge of water. Similar danger mudslides is also noted with water saturation of the ground. Structural disturbances are present distorting the drainage pattern of watershed. The uniqueness of watershed shape specifically of Padada also brings great contribution to the occurrence of flooding in the area.

The three assessed rivers in the region appear to be at varying degree of deterioration based on its abiotic components. Among the three, Kingking is the most degraded considered as very disturbed while Manurigao is the least considered as less disturbed. With almost all of its components rated poor, Kingking has a very disturbed and modified river profile.

Extreme channelization and severe eroded banks which almost levelled to the river bed are evident in the area. When it comes to the surrounding vegetation, most common problem is the lack of canopy allowing full sunlight to reach water surface. Diversity and richness of vegetation along the banks and its capacity to buffer occurring flood appear to be insufficient as well.

For Region 13, as with the regions, all watersheds of the assessed rivers are elongated in shape and thus pose the same danger and carry the same problem on mining and quarrying activities and agricultural cultivation within the watershed.

Most common observed modifications of rivers are the unstable and eroded banks, river channelization and disconnected hydrology.

The assessed rivers from Agusan Norte, Surigao Norte, Davao del Sur and Zamboanga provinces, in particular, have little hydrology and extreme channel alteration exposing large portion of riverbed.

On the other hand, assessment in terms of the surrounding vegetation revealed that most of the rivers are disturbed. Lack of canopy allowing full sunlight to penetrate water surface, and insufficient bank vegetation cover to serve as buffer against flooding are most common observations.

Observed in all assessed rivers, presence of several stressors on hydrologic, physical and landscape conditions are considered major factors of water body modifications. One noted stressor observed common among all assessed rivers in Mindanao is the small to large scale resource extraction. At Zamboanga rivers in particular, quarrying has caused severe channelization resulting to shallower and widened streams. This makes the river even more susceptible to flooding. The occurring open-pit mining at Kingking on the other hand caused the overly destructed landscape and physical structure and reduced amount of vegetation around the river.

All the watersheds are mainly engaged in agricultural production. Rice, corn, coconut and banana are among the most planted and produced crops. These also have corresponding calculated benefit-loss when damage by the flooding calamities. For coconut plantation alone, estimated benefit-loss amounts to Php100,000 per hectare per year when affected by flood. Many of the rivers are also utilized for fishing industries such as the rivers of Zamboanga Peninsula. Almost all watersheds are involved into quarrying and few are involved into mining and timber production.

Other than the occurring economic activities around the area, several characteristics of watershed referred to as the contributory factors were also included in the analysis of study. These said factors (population, stream order, soil type, river slope and land cover) pose significance on the holistic view of possible cause and effect of flooding towards the aspect of environment, society and economy.

Agricultural cultivation has significantly been associated to river shallowing and channelization. Though reported as a quarrying-free town, Bacuag as the most cultivated watershed faces the problem of extreme channel alteration.

Mostly planted with coconut and corn, it was observed to have a similar situation with that of Lower Susquehanna Basin, Maryland where many miles of stream banks are destabilized and sand/silt bars formed in slow moving areas as lands within the basin are developed for agriculture (Millard et al., 1999).

Population density, one considered contributory factor, was found to significantly affect river system through impacts of urbanization. Adverse impact of urbanization to occurrence of flooding can be supported by a survey conducted on Marikina River, Philippines by Abon et al. (2011).

It was revealed that flooding could have been caused by compounding factors such as clogged urban storm drains and stream constrictions due to informal settlements. Similar scenario is seen on what happened last 2013 when Miputak creek of Dipolog city overflowed affecting more than a hundred families.

Moreover, Maya et al. (2012) mentioned that high densities of mines/quarries were connected to the rise in population and developmental activities. Average slope degree in watersheds was as well given significance on river ranking. Steepest slope is associated to more surface runoff and erosion. Water surface with greatest slope was found to have the highest occurring velocities based on a study of hydroecological factors governing surface water flow by Harvey et al. (2009). Moreover, according to Jankauskas et al. (2007), erosion rates are found to increase with slope steepness.

Lower stream orders imply greater possibility of flood occurrence. It is more prone to flash floods since precipitating water directly reaches mainstream and causes immediate flooding especially during heavy rainfalls. On the other hand, it takes more time for runoff to reach higher order streams delaying increase of water and hence of flooding.

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Occurring erosions and vulnerability to runoff is also reflected to the soil type composition of watershed. The clayey and sandy were the two considered soil types in ranking since these were considered to have the most influence in flooding and erosion scenarios of a watershed.

In summary, the 22 rivers assessed may be clustered according to the general problems besetting said rivers, as follows:

Table 2. Clustering of the 22 Critical Rivers

RECOMMENDATIONSEroded banks seem to be a common picture seen on the assessed rivers. Existing sand and gravel quarrying operation plays big factor in the resulting degradation of the river and the insufficiency of vegetation along the stream bank. To regulate over extraction, proper protocol on permit acquisition from the LGUs for quarrying and mining activities is recommended. Responsible Mining Act and other stipulated laws must also be reinforced as guidelines for a sustainable quarrying.

However, implementation is found to have been hindered by conflicts on area jurisdictions due to accidental and inappropriate entitling of riparian lands and rivers, confused by the constant rechanneling of stream. To solve this problem, original river course should be located and determined by revisiting policies and ordinances, which all in all will serve as a challenge to all concerned agencies.

Biotic assessment (vegetation) such as lack of canopy and insufficient amount and thickness of vegetation along the banks are the common observed problems of the rivers. Plants prevent bank erosions and help buffer occurring floods. There should be an agro-reforestation and greenbelt establishment through planting of bamboo and endemic plant species especially of pioneering species (Balete, Bayawak, Dao) along riparian zone. It was also observed that cultivation and open canopy occur in most watersheds, which implies that watershed has less great decrease of natural forests and that upstreams may appear to be nearly denuded. Denuded forest are prone to occurrence of erosions and flashfloods since not enough vegetation will hold and absorb surface water.

Forest conservation in this case should be promoted which may include advocacies on watershed protection as well as movement on re-greening program promoting revegetation on denuded areas and upstream portions with endemic plant species for a resilient landscape.

In addition to the intensive agricultural cultivation along riparian zones, it is recommended that corresponding land use plan of the watershed must be reviewed. This will also include implementation of appropriate soil conservation measures. The conduct of hydrologic analysis for each critical watershed is recommended.

The study will help determine the model of water movement and other significant details within the watersheds. This will include activities on biophysical characterization of watershed and flood forecasting and modelling. Through this, appropriate rehabilitation measures will be determined Poor quality of waters as impact of agricultural cultivation along the stretch of the river will also be addressed through advocacy of soil conservation measures.

There is a need to capacitate LGUs to help address the need for better coordination among government agencies in watershed management. This will cover establishment of an institutional governing board/council composed of sustainable development units (SDUs) to take responsibility

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RECOMMENDATIONS in implementing policies such as the establishment of easement between quarry concessionaires. This will also coordinate the different government agencies in addressing watershed concerns. Moreover, ordinances must empower LGUs to adapt Vulnerability Impact Assessment (VIA), adaptation and mitigation tools in managing watersheds.

It was found out that there is lack of comprehensive data as basis for integrated watershed management. It is recommended to conduct assessment, profiling and monitoring of each watershed. This will revolve more on community-based watershed instrumentation and monitoring system, and capability training to assess the watershed suitability for agricultural intensification.

Watershed characterization.in turn, can be used as a basis for an integrated watershed management plan. Furthermore, it was revealed that there is lack of awareness on ridge to reef approach in watershed management. Therefore, an emphasis on it will be one of the programs. It is proposed as well to monitor the environmental and social aspect of each river to examine how rehabilitation activities fared so far, and to determine the possible initiatives needed to further improve the conditions of these rivers.

Comprehensive watershed assessment studies, particularly on the top three critical rivers in Mindanao, must be done to gain further knowledge on the appropriate rehabilitation strategies and remedial activities in saving these critical rivers. Further in-depth assessments must also be

conducted on riparian corridors of forest landscape to minimize landslides as well as to enhance river quality and hence of the aquatic biota diversity. As observed in this study, social problem is one of those identified factors with significant contribution to environmental impairment. Hence, social issues, which include the residents’ livelihoods and dependence on resource extraction from the river, must be met. Alternative livelihood shall be introduced to the community through agro-forestry and advocacy on sustainable resource extraction through the government units (DSWD, DepEd, DENR, EMB, MGB, LGUs).

As to assessment procedure, it is recommended that future assessment studies on watersheds must first be conducted on watershed level followed by individual assessments of rivers within the watershed. This is to come up with a unified output of rivers contained in a single watershed like that of Layawan River being a tributary of Dipolog River. All tributary streams must also be incorporated to the report and discuss its influence to the watershed as a whole.

Several other parameters and data specifically on history of LGU, flooded area, inundation area and period, climate and rainfall volume and drainage pattern of watershed are recommended. This is to be integrated in the analysis of watershed’s susceptibility and vulnerability towards flooding and to further provide justifications for the need to construct flooding controls. Parameters of presence of bacteria and other organisms are recommended to be included in water quality assessment.

SUMMARY OF RECOMMENDATIONS

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SUMMARY OF RECOMMENDATIONS (CONTINUATION)

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POLICYBRIEF

DA Department of AgricultureDENR Department of Environment and Natural ResourcesDepEd Department of EducationDILG Department of Interior and Local GovernmentDOST Department of Science and TechnologyDPWH Department of Public Works and HighwaysDSWD Department of Social Welfare and DevelopmentEMB Environmental Management BureauGIS Geographic Information SystemGPS Global Positioning SystemLGU Local Government UnitMGB Mines and Geosciences BureauNGA National Government AgencyNGO Non-Government OfficeNIA National Irrigation AuthorityNEDA National Economic Development AuthorityNSO National Statistics OfficeOCD Office of Civil DefensepH Potential HydrogenRBCO River Basin Control OfficeRS Remote SensingTSS Total Suspended Solids

LIST OF ACRONYMS

The MinDA through the Mindanao River Reconstruction Task Force (MRRTF) commissioned the researchers of Central Mindanao University (CMU) being the team of the Mindanao River Reconstruction Ecxperts (MRR Experts) to conduct the study from September to December 2013 for the batch 1 and April to November 2014 for the batch 2.

For further information, please contact

The Policy Formulation Division Mindanao Development Authority (MinDA) 4th Floor SSS Building, JP Laurel Avenue 8000 Davao City

Telephone Nos.: (63-82) 221-2185, 221- 4834Fax No.: (63-82) 221-6920, 221-2180E-mail: info@minda.gov.ph

The MinDA Policy Brief is available online at www.minda.gov.ph\downloads

MinDA Policy Briefs are observations/analyses based on researches and consultations done by MinDA Technical Staff on certain policy issues. The paper is holistic in approach and aims to provide useful inputs for decision-making.