MENANAM POHON UNTUK MEMANEN AIR HUJAN Soemarno - psdl ppsub 2013

MENANAM POHON UNTUK MEMANEN AIR HUJAN Kombinasi teras bangku dan vegetasi pohon untuk memaksimumkan hasil panen air hujan

Sumber: www.thecottagekey.com/watershed.htm Siklus air hujan mengisyaratkan besarnya peluang untuk memanen air hujan

Karakter pohon dapat dimanfaatkan untuk memanen air hujan dan energi matahari sebanyak-banyaknya

SIKLUS HIDROLOGI The hydrologic cycle over land includes interception of precipitation by plant foliage and wood, throughfall and stemflow, transpiration, soil evaporation, canopy evaporation, infiltration, runoff, soil water, aquifer recharge, and snow. These are directly linked to the biogeophysics and also affect temperature, precipitation, and runoff. Diunduh dari sumber: http://www.cesm.ucar.edu/models/clm/hydrologic.html ….. 31/10/2012

EVAPOTRANSPIRASI The total evapotranspiration (ET) can be broken down into the Tr is transpiration, Ei interception evaporation, and Es evaporation from the bare soil and forest floor litter. On an annual basis in a forested environment, transpiration is the dominant component of ET, followed by interception evaporation and then bare-soil evaporation. However, during precipitation events, interception evaporation becomes the dominant component of ET during rainfall and during the hours immediately following precipitation. Diunduh dari sumber: http://www.grin.com/en/doc/268148/observations-of-the-transient-characteristics-of-the-hydrological-balance…..31/10/2012

INTERSEPSI Interception refers to precipitation that does not reach the soil, but is instead intercepted by the leaves and branches of plants and the forest floor. It occurs in the canopy (i.e. canopy interception), and in the forest floor or litter layer (i.e. forest floor interception. Because of evaporation, interception of liquid water generally leads to loss of that precipitation for the drainage basin, except for cases such as fog interception. Diunduh dari sumber: http://www.answers.com/topic/interception….. 3110/2012

Akar Pohon Tree species are not necessarily "deep-rooted" or "shallow-rooted" -- certain species are more or less sensitive to various levels of moisture, oxygen, and minerals. Often roots will "bounce"  off a soil hardpan or a high  water table, forming surface roots where other species may not be able to live at all.  Diunduh dari sumber: http://www.oakwilt.com/articles13001/anatomy2.html ….. 31/10/2012

Trees: The Original Multi-taskers Their beauty inspires writers and other artists. Provide social, ecological, and economic benefits Their leaves and roots clean the air we breathe and the water we drink

Benefits of Trees in Urban Areas Energy: Reduces air conditioning needs up to 30% As windbreaks can lower winter heating costs Lower local air temperatures by transpiring water and shading surfaces. A study in Madison from energy conserving landscapes around a typical residence saved 13% in annual energy savings. Improve air quality: Trees remove (sequester) CO2 from the atmosphere during photosynthesis to form carbohydrates and return oxygen back to the atmosphere as a byproduct. About half of the greenhouse effect is caused by CO2. A single mature tree can absorb about 48 lbs/yr of CO2 and release enough oxygen back into the atmosphere to support 2 people Trees also remove other gaseous pollutants by absorbing them with normal air components such as sulfur dioxide, ozone, nitrogen oxide. Paved Surfaces: Asphalt paving on streets contains a stone aggregate in an oil binder. When heated up, the oil volatilizes, leaving the aggregate unprotected. Trees shade the streets causing the oil not to volatilize as quickly and deter the need of street maintenance (overlayment or slurry sealed) from every 7-10 years to every 20-25 years Traffic safety: Trees enhance traffic calming measures. Tall trees give the perception of making a street feel narrower, slowing people down Trees can serve as a buffer between cars and pedestrians. Increase real estate values: Property values increase 5-15% when compared to properties without trees (depends on species, maturity, quantity and location) Sociological benefits: Trees have the potential to reduce social service budgets, decrease police calls for domestic violence, and decrease the incidence of child abuse. Residents who live near trees have significantly better relations with and stronger ties to their neighbors Trees help create relaxation and well being Trees reduce noise pollution by acting as a buffer and absorbing 50% of urban noise. A community’s urban forest is usually the first impression a community projects to its visitors. A community’s urban forest is an extension of its pride and community spirit. Apartments and offices in wooded areas rent more quickly and have higher occupancy rates. Also their workers are more productive and absenteeism is reduced. Save Energy; Improve air quality Extend life of paved surfaces Increase traffic safety Increase real estate values Increase sociological benefits Protect our water resources

All water is part of this cycle

Storm Water dan Siklus Hidrologi Studies have shown that streams in watersheds with greater than 10% pf their land area in imperviious cover begin to show signs of ecological impairment. As the impervious cover in a watershed approaches 25%, streams become degraded and the water quality, habitat quality and biological diversity occurring in watershed streams are all greatly reduced. Polluted runoff is the number one water quality problem in the Unites State, Wisconsin and Dane County today. UW research has found that urban runoff also contributes about 6% of the N and 17% of the P entering into Lake Mendota. EPA reported to Congress that one-third of US waterways were impaired by storm water runoff which directly affects water quality. EPA now recognizes nonstructural methods, such as increasing tree canopy cover for slowing storm water runoff, as a best management practice or BMP. Urbanization dramatically alters the hydrologic cycle Increases runoff Increases flooding frequency Decreases infiltration and groundwater recharge Nationwide impervious surfaces have increased by 20% in the past 20 years

More Trees Means Less Runoff Some Statistics Arkansas stormwater runoff reduction valued at $43 million in capital improvement savings (represents $2/ cubic ft cast to contain storm water runoff). For every 5% of tree cover added to a community, storm water is reduced by approximately 2% Fayetteville, Arkansas: increasing tree canopy from 27-40% reduced their storm water runoff by 31% South Miami residential study found that a 21% existing tree canopy reduces the storm water runoff by 15%

Bagaimana pohon mengendalikan “Stormwater”? Above ground effects: Interception, evaporation and absorption of precipitation Ground surface effects: Temporary storage Below ground effects: Infiltration, permeation and filtration

Infiltrasi dan perkolasi air-hujan dalam tanah merupakan dua proses hidrologis yang sangat diperbaiki oleh adanya vegetasi pohon

EFEK POHON TERHADAP LINGKUNGAN DI ATAS TANAH Absorption of a small portion into leaves or stems The delay of precipitation onto the ground can dampen the peak of runoff amounts from storms which are most intense at their outset, before the storage capacity of the tree canopy is reached. The amounts of the effects on runoff are primarily dependent on season (for deciduous trees), on the leaf area index of a tree and on its density of twigs and branches. The evaporation rate is also crucial in influencing the above-ground effects. This rate is determined by air temperature, humidity and the intensity of solar radiation. With a large amount of leaf-surface area exposed to the sun and wind, water loss from the leaves is high. By slowing the storm water flow, the flow of water is spread over a greater amount of time (time of concentration) and the impact of a storm on the facilities built to handle it at any one time is smaller. Stemflow is a relatively small percentage of total precipitation Intercept rainwater on leaves, branches and trunks – slowing its movement Evaporation of some of this intercepted precipitation of the tree surfaces

Efek Pohon terhadap Lingkungan Bawah Tanah These effects on runoff are influenced primarily by the size and age of trees. Older, larger trees generate more litter per area and modify the microtopography around them more dramatically. Site management is also important, especially whether organic litter is removed or retained on a site. Roots and trunk bases of mature trees tend to create hollows and hummocks on the ground Leaf litter and other organic matter can hold precipitation and stemflow on a site, reducing the amount and peak rates of runoff

Lingkungan Bawah Tanah Efek Pohon terhadap Lingkungan Bawah Tanah Organic material from leaf litter and other tree detritus tends to increase infiltration rates by increasing pore spaces in soil Organic material also increases the moisture-holding capacity of these sites Root mats of trees also tend to break up most soils further improving infiltration and moisture-holding capacity

EFEK LINGKUNGAN-BAWAH-TANAH Deep roots tend to improve the rates of percolation of water from upper soil horizons into lower substrates Trees take up water through their roots that is eventually transpired onto leaf surfaces and evaporated Tree roots act as natural pollution filters (biofilters) using nitrogen, phosphorus and potassium

TAJUK POHON - KENYAMANAN Set to protect a community’s green infrastructure and maximize the environmental benefits For metropolitan areas east of the Mississippi Average tree cover for all land use 40% Suburban residential 50% Urban residential 25% Central business districts 15%

Ruang terbuka hijau – Taman pohon buah-buahan MULTIPURPOSES …? Ruang terbuka hijau – Taman pohon buah-buahan

COMPLICATING FACTORS Presence of soil compaction Compaction or textural discontinuities are frequently caused during building and lawn construction. May greatly impact the rate of infiltration and permeability of the soil. Research at UW has shown that infiltration is reduced to about 35% of that of undisturbed sites. Lawn sites that had stratification in the top 45 cm caused by the addition of fill or the speading of subsoil material during basement construction over the original soil profile and then finishing the lawn with a layer of topsoil. Presence of soil compaction Presence of soil textural discontinuity Has the site been disturbed in the past? Management of the ground surface Is litter layer removed? Is soil surface exposed in winter? How much of the surface is like a natural forest? (number and size of trees)

PERGERAKAN LENGAS TANAH Matric forces are the forces that affect the free energy of soil water by the attraction of the soil solids for water. These reduce the free energy due to suction and tension respectively. Gravity tends to move water from a higher elevation to a lower level. Total potential of soil water is the sum of matric, osmotic, and gravitational forces plus other minor forces. Osmotic forces also reduce the free energy of the soil solution as it is the attraction of ions and other solutes (salts) for water. This is a lesser force than the matric forces. Field capacity water is the plant available water Forces affecting the energy of soil water Matric force (absorption and capillary) Gravity Osmotic forces Field Capacity is the amount of water held in the soil after gravitational water had drained away Movement of water is the soil is controlled : Gravitational forces if saturated Matric forces if unsaturated

Tanah mempengaruhi Infiltrasi air hujan Internal characteristics of the soil include: pore space, degree of swelling soil colloids, organic mater content. Only when the rainfall intensity exceeds the infiltration capacity of a soil can runoff occur. By virtue of the spongelike action of most forest floors and the high infiltration rate of the mineral soil below, there is little opportunity for surface runoff of water in mature forests. Infiltration is the mode of entry of all water into the soil Rate of infiltration determined: Initial water content Surface permeability Internal characteristics of the soil Intensity and duration of rainfall Temperature of soil and water

Tanah mempengaruhi Infiltrasi Soil compaction reduces the infiltration rate Microrelief under trees provides catchment basins during heavy rains Removal of litter layer reduces the infiltration rate Forest soils have a high percentage of macropores The frost type found in forest soils promotes infiltration year-long

PENTINGNYA SERESAH DI PERMUKAAN TANAH * The litter layer absorbs several times its own weight of water, breaks the impact of raindrops, prevents agitation of the mineral soil particles and discourages the formations of surface crusts. It also leads to an increase in the organic matter content of the top mineral layer and creates a habitat for many of the soil fauna to feed and hide in which in turn increases the porosity of the soil. The variety, numbers and activity of soil organisms generally is much greater in forest soils than in agricultural soils or in lawns. It also slows down the lateral movement of surface water permitting a longer period for infiltration. Absorbs several times its own weight Breaks the impact of raindrops Prevents agitation of the mineral soil Discourages formation of surface crusts Increases soil biotic activity Increases incorporation of organics Slows down lateral movement of water

POROSITAS TANAH Develop in old root channels or from burrows and tunnels made by insects, worms or other animals Lead to better soil structure Increases organic matter incorporation Increases percolation rates and root penetration

TANAH DI BAWAH TEGAKAN HUTAN Granular Found in woodland soils with litter May be more permeable Honeycomb Has loose porous structure Found in highly aggregated soils and also formed in organic layers and litter layers

AIR-TANAH-TANAMAN The proportion of the soil occupied by water and air is referred to as the pore volume. The pore volume is generally constant for a given soil layer but may be altered by tillage and compaction. The ratio of air to water stored in the pores changes as water is added to or lost from the soil. Water is added by rainfall or irrigation. Water is lost through surface runoff, evaporation (direct loss from the soil to the atmosphere), transpiration (losses from plant tissue), and either percolation (seepage into lower layers) or drainage.