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Thesis, CO2 adsorption/emissions
Land Classes and Areas
Impact, including CO2 emission
Problems, including CH4 emissions
Water Management System
These tables cover hydrological land qualities
and soil characteristics with
important effects on design and the potentials.
The Land Qualities are also subject to dynamic processes, not
in the least because of changes in the canal lay-out and design, upgrading of
canals and infra-structure,
or by environmental changes, such as the disappearance of peat domes. It is hoped that the tables will contribute to a better understanding
of the required needs and the expected effects of upgrading of the Tidal Lowland
Schemes. The Tables should be used in SID's (Surveys, Investigations and
Design) both at Micro as at Macro level.
A Land Unit in
the Tidal Lowlands will be a combination of two Hydrological Land Qualities with
one Flooding Type Land Quality , one Drainability Land Quality and one Soil
Type Land Quality. So far little experience exists to define land units based
on the land qualities as described in the tables below. Experience will learn
what will be the most relevant combinations of land qualities.
Limits of land qualities based on
Canal Distances as mentioned in the tables below are arbitrary. They depend in
fact on design and lay-out of the system and are strongly influenced by the
tidal range of the near-by river. Modeling of the each canal system is possible
and would be recommended to determine the limits for each hydrological land
quality. For practical reasons I introduce hereunder the canal distance limits
based on experience. It should be realised that for each area and scheme lay-out
they might be different and the limits should be used as an indication only.
The classification of the Land Qualities takes into
account only the present
land conditions. But in cases of flooding
problems it assumes that in the present conditions
there is already flood protection or
there might be dike construction planned in the
future. See Land Quality 1.2.1 and 2.1.2
Hydrological land qualities for developed Tidal Lowlands
Hydrological qualities in developed areas
Hydrological/ Distance qualities
Recommendations and Potentials for Use
1.1 Saline Intrusion
with 3-6 months saline intrusion in canals
for only one crop rice per year. Extra attention should be given to domestic
water supply. Tree crops might be preferred here in areas with sufficient
effective drainage depth. In areas with a small tidal range : fish/shrimp
ponds can be recommended.
with 3 months or less saline intrusion in canals
Potentials for two rice crops per year. These lands cover the largest area
in the developed Tidal Lowlands.
1.2 Areas with small
tidal range of <30 cm during wet season in adjoining Primary/Secondary
canal; Distance to canal< 1.5 km
(When distance to
Primary/Secondary canal is more than 1.5 km the area is not considered to
belong to the developed Tidal Lowlands.)
with canal distance <8 km from tidal river
tidal ranges in well maintained canals at less than 8 km canal distance from river means
usually that you are in the upper reaches of the tidal stretch of the river,
close to the floodplain river stretch.
usually bordering Lebak (floodplain) areas which need dike
for flood protection. Adapted cropping calendar.
Great care should be taken on acid sulphate soils. Pump irrigation essential
on these soils. One-way flow in canals essential
with canal distance >8 km from tidal river
small tidal range here usually means you are still in the tidal stretch of
the river, but only too far away from river. Extra inputs for
controlled water flow in the canals are required.
care should be taken on acid sulphate soils. Determine if there is a source
to keep the soil wet in the dry season (Flooding
Type 2.2) Pump irrigation is usually essential when lands are not subject to
surface flows from forest/upland. Major Primary canal required parallel to
rivers with controlled one-way flow.
Areas with a tidal range of >30 cm during wet season in adjoining
River/Primary / Secondary Canal; Distance to canal < 1.5 Km
Areas bordering the Tidal Stretch of the rivers
Tidal Lowland Schemes are found in these areas.
Land Quality for developed Tidal Lowlands
Potentials for Use
2.1 Tidal Irrigation
Tidal Flooding type
Canal distances will
influence the potentials for tidal irrigation and the type of tidal
with a canal distance <1.5 km from tidal river, no deep flooding.
manageable areas, open canals for water supply and drainage. These areas are
usually occupied by local farmers, who settled first.
with a canal distance <1.5 km from tidal river, deep flooding
for flood protection required. Control structures
in dike required.
with a canal distance >1.5 km from tidal river.
irrigation depends here on the combined effect of rainfall,
relatively small canals, high tides and
the low position of the land.
should be taken for “Over-Drainage” when enlarging canals,
or when making short-cuts to rivers. Control structures to control
water levels are in this case always essential. l
Surface flows from nearby peat forest/upland
subject to wetting by surface flows.
of “Over-Drainage” when enlarging canals or after disappearance
of the peat dome. Controlled flow required by
construction of dikes and structures.
2.3 No-Tidal Irrigation.
Tidal Flooding type
not subject to wetting by surface flows. Also there is
no tidal irigation.
intense leaching in On-Farm water management system required for
muck/pyrite soils.No dead-ended canals and one-way flow in
major canals are important in places at more
than 1.5 km canal distance from river.
Qualities for developed Tidal Lowlands
||Canal distance effect
3.1 Lands without sufficient drainage potential
Effective drainage depth
peat has disappeared)
distance less than 1.5 km from tidal river.
areas can usually still be drained during low tide.
be usually cultivated. Multiple
connections to nearby river required to increase
the drainage potential. Tree crops can
grow only on raised beds.
distance more than 1.5 km from tidal river.
case the time available for drainage at low tide is too short for proper
recommended here for agricultural development. These
areas include major parts of the peat soils. Sustainable forestry
with minor drainage inputs may be an option
3.2. Lands with sufficient drainage potential
depth >30 cm (after peat has disappeared)
3.2.1. Effective drainage depth 30-60 cm. Canal distance less than 1.5 km from
During low tide more time is available
for drainage and drainage potential compares with land quality 3.2.3.
crops and rice crops can be recommended here.
3.2.2. Effective drainage depth 30-60 cm. Canal distance more than 1.5 km from
During low tide less time is
available for drainage
crops are mainly recommended here. Tree crops can grow only on raised beds.
3.2.3. Effective drainage depth >60 cm
areas there is never a drainage problem.
cases tree crops might be preferred, but in old, poorly drained, marine deposits
usually there is a preference for rice crops.
Effective drainage depth is the difference in average
land level and the average water level in the adjoining Secondary
canal with tidal influence. After rehabilitation of the canals the Effective Drainage depth might
improve, so it also a dynamic land quality.
Soil Types Land
Qualities for developed Tidal Lowlands
4.1 Muck/pyrite soils
4.1.1. Lahan Potensial
the present conditions there is a balance
between oxidation and leaching to keep the soil non-acid. It is
essential that unripe soils in lahan potensial,
characterized by a low bulk density, should be made more
mature by a shallow on-farm water management system.
These soils will become more mature by promoting, during the dry season,
a drop of the groundwater tables to 60 cm below
the surface.. Ripe soils will make pump irrigation possible in
combination with tractor use and by creation of
plough-layer. (Unripe soils can not maintain water layers on the field.)
4.1.2. Lahan Sulfat Asam
is in the present conditions Insufficient potential
for leaching and flushing. By introducing an improved
on-farm water management system combined with mechanized land preparation,
double connected canals and one-way flow flushing in the
canals, these lands will return to
4.2. Non-Pyrite soils
4.2.1. Recent Marine/Riverine Sediments
Most of these lands have
a potential for rice or deep fish ponds
4.2.2. Old Marine/Riverine
These lands are mainly
used as rice lands. No deep plowing recommended because of hazard of mixing
topsoil with toxic (Aluminium) subsoil.
4.3. Peat soils
4.3.Lahan Gambut (Indonesian classification) With
sustainable drainage potential
drainage depth (>30 cm) after subsidence
Can be used for tree
4.4. Lahan Gambut (Indonesian classification) With no
sustainable drainage potential.
drainage depth (<30 cm) after subsidence
No agricultural use possible at present. Sustainable use only possible when
groundwater tables can me maintained above 30-40 cm below surface. Ramin
trees might be an option in these conditions.
4.4 Whitish Low Fertility
Very low agricultural
potentials. Improved drainage might provide potential for Melaleuca
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