Rains Recharge & Replenish

By Michelle Domocol @inflourish_
Back to Inflourish: Cebu Blog

This past August and most of September, we experienced a terrible heatwave and extended drought. Fortunately, the rains have returned. The recent drought reminds us of Cebu’s vulnerable, declining groundwater reserves. Excessive groundwater extraction, river pollution, and intensive irrigation historically threaten our water supply. Additionally, the continued construction of impervious surfaces worsens our groundwater crisis. Pouring cement over every urban surface stops rain from naturally seeping into our soils and refilling groundwater.

During August, Healing Present’s forest shrubs and gardens suffered from dehydration. Luckily, our long-standing water conservation methods delayed plant root death and irreversible dehydration. Our water reserves helped plants recover. Water conservation also maintains supplies for daily cooking, bathroom, and property maintenance. Our water-saving and storage methods include aboveground rainwater tanks, retention ponds, mulching, and groundcover. We plan to add percolation pits, recharge ponds, and drought-resistant groundcover.

Below are some of the main features of our water management techniques. Perhaps you want to protect your land, family, or community from seasonal water shortages. This may inspire you to integrate methods that maximize rainwater storage and groundwater recharge during wet/typhoon seasons.

Groundcover & Vegetation

Groundcovers are low-growing plants that can spread quickly and cover bare soil. Vegetation like shrubs and trees soften the impact of heavy rainfall and replenish natural water reserves. As their leaves and root networks increase, they hold soil together. Groundcover and vegetation help soil absorb stormwater and refill groundwater. During torrential downpours, that means less water erosion and no landslides. Groundcover can also keep the soil moist. This essential reservoir of moisture helps plant roots survive droughts and recover when rain returns. Here are some examples of groundcover we install in our gardens and forest pockets:

Common native and naturalized groundcover species in the Philippines.

Retention and Recharge Ponds

Retention ponds collect rainwater throughout the year. They are typically constructed with a cement or plastic pond liner. The liner blocks water from flowing into the soil. If our aboveground rainwater tank supply or groundwater levels were low, we could pump water from these ponds for activities like plant irrigation. In contrast, recharge ponds do not have a liner. They are seasonal dug-out ponds that store stormwater during the wet season. In Healing Present, these ponds can feed forest roots, springs in underground caverns, and groundwater.
Inspired by water management in South Asia, recharge ponds are built in sloping or low-lying areas. Like the groundcover technique, they protect us from unstable soils and landslide damage. The ponds are surrounded by groundcover, shrubs, and trees to increase rainwater absorption. Combing techniques ensure rainwater is not wasted, flowing off the property and causing flood damage. Below is an example of a standard recharge pond:

This Recharge Pond is circular with a diameter of 3 meters and a depth of 1 meter. The pond walls should be no more than 45-degree angles to prevent collapse. You can add native aquatic plants inside the pond to increase rainwater aeration and filtration. Aquatic plant species include Typha spp., Nelumbo spp., and Cyperus spp.

Percolation Pits

Percolation pits are special rainwater drainage basins. They filter surface runoff and stormwater before it refills groundwater. Percolation pits are built in areas with high rainfall absorption and permeable soil. You can install percolation pits next to buildings so they receive water from roof gutters and rainwater drainage pipes. Or you can place them in the middle of gardens and forests on sloping areas with high rainfall. Percolation pits should be built in soils with high water infiltration and percolation rates. Simple soil tests determine if rain would easily travel through the percolation pit layers, into surrounding soil, and towards groundwater. Below is a diagram of a percolation pit:

The percolation pit can have layers of sand, stone, and rocks to filter rain before it reaches the groundwater.

I hope this inspires you to find stormwater solutions and water-saving methods. Positive changes can preserve water supplies and divert pressure off our finite groundwater reserves.

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Renewal with Rainwater Harvesting

By Michelle Domocol @inflourish_
Back to Inflourish: Cebu Blog

In Healing Present’s (HP) farm and reforestation projects, we install different kinds of rainwater harvesting systems to:

In Cebu, reducing our use of groundwater can help our surrounding watershed renew its freshwater supply.  In some areas, groundwater can be too saline or have pollution. Rainwater supplies can help you avoid using saline or contaminated groundwater. In general, Cebu residents, land managers, renters, and homeowners need to put less stress on our watershed and groundwater supply. Cebuanos, in uplands and urban areas, have experienced droughts and extreme dry seasons.  Urban residents and farmers in Cebu’s mountains have seen decades of seasonal water scarcity, diminishing groundwater recharge, water quality deterioration, cost-prohibitive water treatment services, and failing drainage infrastructure from city water distribution lines. Rainwater systems offer an option to gain some relief from those water supply issues. 

In one of HP’s gardens, a simple stand alone rainwater collection barrel is connected to drip irrigation tubing and sprayers that waters a garden with native trees, gingers, cannas, and other shrubby vegetation.

In Healing Present sites, we use the rainwater to minimize our reliance on deep well groundwater. When we do this, groundwater can:

With simple rainwater harvesting devices like rainwater barrels and underground storage water tanks, HP spends less money and electricity on city-sourced water, external water treatment services, and water pumping stations.  In our farm and forest projects, we attach rain barrels and tall rainwater water collection towers to plant irrigation tubing, garden hoses, plant nursery washing stations, sinks, showers, and toilet tanks.

Faucets, hoses, and irrigation tubing are directly attached to the barrel.
Drip irrigation tubing directed to individual pots.
Little sprayers attached to irrigation tubing so water is directed to plants’ soil.

Households can attach small rain barrels, above-ground tanks, or large rainwater towers to a filtration system so we have an independent supply of drinking water. Plus any pump system or filtration component can be powered with solar panels to reduce your electricity costs.

HP Rainwater Tank Tower
Underground Rainwater Collection Tank

  • We identify a location for the rainwater collection device. We make sure the device can receive an ample amount of rain.  Sometimes we add a platform or position the collection tank above the area we want to irrigate. Or if the rainwater is coming from a roof, we may improve the rain gutters and add pipes to direct the water straight into the collection device.
  • We add irrigation tubing or mainline pipes depending on where the water needs to go. For example if the water is intended for a garden then we attach irrigation tubing, valves, and sprayers to the rainwater collection system. We always add a faucet or valve to control the flow of water from the tank or barrel.  Rainwater tanks can be cylindrical, boxy, customized to fit underground, or be decorated to blend in with your landscape. 
  • You can add screens and nets to reduce the mosquito population and leaves that can enter your rainwater collection device.
  • If your storage tank is located underground, you may need to add a pump to direct water towards a particular garden, pipe system, or building.
  • Make sure to add pipes or extra storage devices to divert or store the overflow of rainwater. 

In HP, we depend on rainwater tanks and reservoirs to support our growing reforestation projects.  Young trees, shrubs, and potted plants need water to survive and develop strong root systems. After these young trees develop into a thick canopy, they can increase rainfall, absorb floodwaters, reduce storm damage, and stabilize our future water supplies. 

In the coming months, we have plans to improve our rainwater harvesting systems.ย  We want to install more underground reservoir tanks to store freshwater for future droughts.ย  We also want to add more tanks to store rainwater overflow. We will most likely use cement tanks and custom made corrugated metal tanks to store more rainwater. This helps us efficiently harvest during rainy seasons.

I hope this inspires you to assess your household, farm, or, apartment for rainwater collection opportunities. See if you would like to supplement or improve your household water supply with a rainwater collection system. It can start with one humble rainwater barrel and progress to larger rainwater harvesting systems.

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