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ure 
  
  
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IAPRS & SIS, Vol.34, Part 7, "Resource and Environmental Monitoring", Hyderabad, India,2002 
  
Thematic maps are used to prepare a mask that filters out areas 
where the crop is surely not grown (parks, reserves, urban areas, 
water bodies, forests, etc.). For the example shown (Ghana; 
Figure 1), also a 100 m pixel radar image was used for the 
southern humid tropical areas to counter-balance cloud 
problems faced for that region with the NDVI images. The radar 
image was classified by comparing it with Aster images (15 m) 
to identify pixels representing trees. Such pixels were added to 
the mask. 
Analysis is based on the GIS procedure to count by 
administrative area the number of pixels belonging to each of 
the NDVI and suitability classes while excluding pixels that are 
masked out. This produces a matrix of data that is tested 
through fore-ward step-wise multiple regression for its relation 
with the tabular agricultural statistics. The generated function is 
in turn used to generate the required crop map (Figure 1). An 
iterative procedure to re-define the number of useful NDVI 
classes to generate is now recommended. 
One can consider to add to the generated output additional land 
use statistics as available in Census or annual agricultural 
reports, like yields, NPK use, area irrigated, etc. 
5. OPTIONS TO IMPROVE LAND USE SURVEYS 
This activity deals with novel methods to support gathering 
through surveys selected land use information, and aim to study 
ultimately in detail crop production land uses (where fields are 
present!). 
Multiple area frame land use surveys at country level use, after 
stratification and random selection of primary survey units, air 
photographs (AP's) as guide to sample plots (already adopted in 
many developing countries). Survey preparation is costly and 
laborious. Use of new high resolution RS-images (e.g. Aster of 
15m) and multi-temporal NDVI images (of lkm) provide 
options to identify individual fields directly, to mask natural 
cover types present, and to differentiate types of cropping 
patterns followed. At present Aster images are very cheap (vs. 
non-availability of AP's or forced use of old AP's), while 
decadal 1-km resolution NDVI images are completely free of 
costs. 
The approaches aim to develop new standards that offer huge 
savings of time and costs while improving accuracy and detail. 
Clearly further research is required to fully test, explore and 
integrate suggested methods. Once done, improved "survey 
guidelines" must emerge. 
To explore activities, some basic concepts must be provided. 
A Land Use System (LUS) is defined as: "A specific land use, 
practiced during a known period of time on a known unit of 
land that is considered homogeneous in land resources" (de Bie 
2000). A land use system (Figure 2) is composed of two main 
elements: land and land use. Land Use is defined as: "A series 
of operations on land, carried out by humans, with the intention 
to obtain products and/or benefits through using land resources" 
(de Bie 2000). Land use purpose(s), i.e. the intended products or 
benefits of land use, and an operation sequence, i.e. a series of 
operations on land in order to realize one or more set land use 
purposes, characterize land use. 
To understand the “operation sequence” better, some definitions 
follow: 
  
  
  
| Context [> Socio-Economical Conditions = Land un Goats _| 
User(s) 
  
  
Bio-Physical Conditions 
  
  
  
  
  
  
  
  
  
Decision making 
equirements & | Land Use System i / planning 
Suitability 
Land | Land Used Y 
Soil / Terrain 
: Land Use 
Climate / Weather Purpose(s) 
Productivity Vegetation 
(Crops / Flora) impaston ou 
Outputs Inputs / 
/ *—  |wildife(Fauna) FH Operation «4— implements 
Benefits Infrastructure Sequence L 
  
  
  
  
  
  
  
  
Impact on/from 
the environment 
interaction with 
Other Land Use Systems | secondary production 
| systems 
Y 
| Livestock Systems | 
Figure 2. Conceptual Structure of a Land Use System (LUS) 
providing Practical ‘Study Entries’ (de Bie 2000). 
  
  
  
  
  
  
Operations (Figure 3) are intended to modify land aspects, e.g. 
soil characteristics or land cover. Some modifications are 
permanent (constructing infrastructure) whereas others can be 
of a temporary nature, e.g. the successive land cover types ‘bare 
soil, crop, and stubble’ are brought about by ‘ploughing, 
planting and harvesting’. Impacts of operations may exceed the 
intended effects resulting in, e.g. erosion, accumulation of 
pesticide residues, loss of soil fertility, etc. Four basic types of 
impact can be distinguished; they relate to soil/terrain, 
flora/fauna, infrastructure and air. 
Observations (Figure 3) are defined as: "A record of one or 
more land conditions that are relevant to the performance of a 
land use system." Examples of observations are "water shortage 
during crop establishment", or "recorded limitation of the 
rooting depth of crops". Observations can be made at any 
moment during the life span of the land use system; the land 
user makes them often and information about such observations 
is obtained through interviews. Observations frequently provide 
important information on the temporal properties of the land use 
system; such information is not stored in databases that contain 
only static or generalized data on land. 
  
Operation Sequences 
1969 1975 1979 1988 1989 
L | | 
  
Grazing ' Fallowing j Rainfed Cropping 
  
  
  
  
  
  
1988 89 
E i Lol | ] ] | | Luo 
SF (MT AM TS | |A|S STATS 
Operations 
NPK Applic. 
*— rb 
Ploughing Seeding Weeding Harvesting Fallow 
+ + + + «o o4 
  
1 Observations 
  
++ uw + 
Rill Erosion Germination 4 Pest Attack 
Trampling Hail Storm 
Figure 3. Illustrating Land Use Operations and Observations.